Point cloud data transmission device, point cloud data transmission method, point cloud data reception device, and point cloud data reception method

ABSTRACT

Disclosed herein is a point cloud data transmission method. The transmission method may include encoding the point cloud data, encapsulating the point cloud data, and transmitting point cloud data. Disclosed herein is a point cloud data reception device. The reception device may include a receiver configured to receive the point cloud data, a decapsulator configured to decapsulate the point cloud data, and a decoder configured to decode the point cloud data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/959,755, filed on Jan. 10, 2020, which is herebyincorporated by reference as if fully set forth herein.

BACKGROUND Field of the Invention

Embodiments provide a method for providing point cloud content toprovide a user with various services such as virtual reality (VR),augmented reality (AR), mixed reality (MR), and autonomous drivingservices.

Discussion of the Related Art

A point cloud is a set of points in a three-dimensional (3D) space. Itis difficult to generate point cloud data because the number of pointsin the 3D space is large.

A large throughput is required to transmit and receive data of a pointcloud.

SUMMARY

An object of the present disclosure is to provide a point cloud datatransmission device, a point cloud data transmission method, a pointcloud data reception device, and a point cloud data reception method forefficiently transmitting and receiving a point cloud.

Another object of the present disclosure is to provide a point clouddata transmission device, a point cloud data transmission method, apoint cloud data reception device, and a point cloud data receptionmethod for addressing latency and encoding/decoding complexity.

Embodiments are not limited to the above-described objects, and thescope of the embodiments may be extended to other objects that can beinferred by those skilled in the art based on the entire contents of thepresent disclosure.

To achieve these objects and other advantages and in one aspect of thepresent disclosure, a method for transmitting point cloud data mayinclude encoding point cloud data, encapsulating the point cloud data,and transmitting the point cloud data. In another aspect of the presentdisclosure, a device for receiving point cloud data may include areceiver configured to receive point cloud data, a decapsulatorconfigured to decapsulate the point cloud data, and a decoder configuredto decode the point cloud data.

A point cloud data transmission method, a point cloud data transmissiondevice, a point cloud data reception method, and a point cloud datareception device according to embodiments may provide a good-qualitypoint cloud service.

A point cloud data transmission method, a point cloud data transmissiondevice, a point cloud data reception method, and a point cloud datareception device according to embodiments may achieve various videocodec methods.

A point cloud data transmission method, a point cloud data transmissiondevice, a point cloud data reception method, and a point cloud datareception device according to embodiments may provide universal pointcloud content such as an autonomous driving service.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 illustrates an exemplary structure of a transmission/receptionsystem for providing point cloud content according to embodiments;

FIG. 2 illustrates capture of point cloud data according to embodiments;

FIG. 3 illustrates an exemplary point cloud, geometry, and texture imageaccording to embodiments;

FIG. 4 illustrates an exemplary V-PCC encoding process according toembodiments;

FIG. 5 illustrates an example of a tangent plane and a normal vector ofa surface according to embodiments;

FIG. 6 illustrates an exemplary bounding box of a point cloud accordingto embodiments;

FIG. 7 illustrates an example of determination of individual patchpositions on an occupancy map according to embodiments;

FIG. 8 shows an exemplary relationship among normal, tangent, andbitangent axes according to embodiments;

FIG. 9 shows an exemplary configuration of the minimum mode and maximummode of a projection mode according to embodiments;

FIG. 10 illustrates an exemplary EDD code according to embodiments;

FIG. 11 illustrates an example of recoloring based on color values ofneighboring points according to embodiments;

FIG. 12 illustrates an example of push-pull background filling accordingto embodiments;

FIG. 13 shows an exemplary possible traversal order for a 4*4 blockaccording to embodiments;

FIG. 14 illustrates an exemplary best traversal order according toembodiments;

FIG. 15 illustrates an exemplary 2D video/image encoder according toembodiments;

FIG. 16 illustrates an exemplary V-PCC decoding process according toembodiments;

FIG. 17 shows an exemplary 2D video/image decoder according toembodiments;

FIG. 18 is a flowchart illustrating operation of a transmission deviceaccording to embodiments of the present disclosure;

FIG. 19 is a flowchart illustrating operation of a reception deviceaccording to embodiments;

FIG. 20 illustrates an exemplary architecture for V-PCC based storageand streaming of point cloud data according to embodiments;

FIG. 21 is an exemplary block diagram of a device for storing andtransmitting point cloud data according to embodiments;

FIG. 22 is an exemplary block diagram of a point cloud data receptiondevice according to embodiments;

FIG. 23 illustrates an exemplary structure operable in connection withpoint cloud data transmission/reception methods/devices according toembodiments;

FIG. 24 illustrates a relationship between a 3D region of a point cloudand regions on a video frame according to embodiments;

FIG. 25 shows the structure of a bitstream containing point cloud dataaccording to embodiments;

FIG. 26 shows the structure of a bitstream containing point cloud dataaccording to embodiments;

FIG. 27 shows a V-PCC unit and a V-PCC unit header according toembodiments;

FIG. 28 shows the payload of a V-PCC unit according to embodiments;

FIG. 29 shows a V-PCC parameter set according to embodiments;

FIG. 30 shows the structure of an atlas bitstream according toembodiments;

FIG. 31 shows an atlas sequence parameter set according to embodiments;

FIG. 32 shows an atlas frame parameter set according to embodiments;

FIG. 33 shows atlas frame tile information according to embodiments;

FIG. 34 shows supplemental enhancement information (SEI) according toembodiments;

FIG. 35 shows 3D bounding box SEI according to embodiments;

FIG. 36 shows a 3D region mapping information SEI message according toembodiments;

FIG. 37 shows volumetric tiling information according to embodiments;

FIG. 38 shows volumetric tiling information objects according toembodiments;

FIG. 39 shows volumetric tiling information labels according toembodiments;

FIG. 40 shows the structure of an encapsulated V-PCC data containeraccording to embodiments;

FIG. 41 shows the structure of an encapsulated V-PCC data containeraccording to embodiments;

FIG. 42 shows a V-PCC sample entry according to embodiments;

FIG. 43 shows track replacement and grouping according to embodiments;

FIG. 44 shows a structure of a 3D region mapping information accordingto embodiments;

FIG. 45 shows a structure of a 3D region mapping information accordingto embodiments;

FIG. 46 shows a structure for encapsulating non-timed V-PCC dataaccording to embodiments;

FIG. 47 illustrates a point cloud data transmission method according toembodiments; and

FIG. 48 illustrates a point cloud data reception method according toembodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. The detailed description, which will be givenbelow with reference to the accompanying drawings, is intended toexplain exemplary embodiments of the present disclosure, rather than toshow the only embodiments that can be implemented according to thepresent disclosure. The following detailed description includes specificdetails in order to provide a thorough understanding of the presentdisclosure. However, it will be apparent to those skilled in the artthat the present disclosure may be practiced without such specificdetails.

Although most terms used in the present disclosure have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentdisclosure should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

FIG. 1 illustrates an exemplary structure of a transmission/receptionsystem for providing point cloud content according to embodiments.

The present disclosure provides a method of providing point cloudcontent to provide a user with various services such as virtual reality(VR), augmented reality (AR), mixed reality (MR), and autonomousdriving. The point cloud content according to the embodiments representdata representing objects as points, and may be referred to as a pointcloud, point cloud data, point cloud video data, point cloud image data,or the like.

A point cloud data transmission device 10000 according to embodiment mayinclude a point cloud video acquirer 10001, a point cloud video encoder10002, a file/segment encapsulation module 10003, and/or a transmitter(or communication module) 10004. The transmission device according tothe embodiments may secure and process point cloud video (or point cloudcontent) and transmit the same. According to embodiments, thetransmission device may include a fixed station, a base transceiversystem (BTS), a network, an artificial intelligence (AI) device and/orsystem, a robot, and an AR/VR/XR device and/or a server. According toembodiments, the transmission device 10000 may include a device robot, avehicle, AR/VR/XR devices, a portable device, a home appliance, anInternet of Thing (IoT) device, and an AI device/server which areconfigured to perform communication with a base station and/or otherwireless devices using a radio access technology (e.g., 5G New RAT (NR),Long Term Evolution (LTE)).

The point cloud video acquirer 10001 according to the embodimentsacquires a point cloud video through a process of capturing,synthesizing, or generating a point cloud video.

The point cloud video encoder 10002 according to the embodiments encodesthe point cloud video data. According to embodiments, the point cloudvideo encoder 10002 may be referred to as a point cloud encoder, a pointcloud data encoder, an encoder, or the like. The point cloud compressioncoding (encoding) according to the embodiments is not limited to theabove-described embodiment. The point cloud video encoder may output abitstream containing the encoded point cloud video data. The bitstreammay not only include encoded point cloud video data, but also includesignaling information related to encoding of the point cloud video data.

The encoder according to the embodiments may support both thegeometry-based point cloud compression (G-PCC) encoding scheme and/orthe video-based point cloud compression (V-PCC) encoding scheme. Inaddition, the encoder may encode a point cloud (referring to eitherpoint cloud data or points) and/or signaling data related to the pointcloud. The specific operation of encoding according to embodiments willbe described below.

As used herein, the term V-PCC may stand for Video-based Point CloudCompression (V-PCC). The term V-PCC may be the same as Visual VolumetricVideo-based Coding (V3C). These terms may be complementarily used.

The file/segment encapsulation module 10003 according to the embodimentsencapsulates the point cloud data in the form of a file and/or segmentform. The point cloud data transmission method/device according to theembodiments may transmit the point cloud data in a file and/or segmentform.

The transmitter (or communication module) 10004 according to theembodiments transmits the encoded point cloud video data in the form ofa bitstream. According to embodiments, the file or segment may betransmitted to a reception device over a network, or stored in a digitalstorage medium (e.g., USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.). Thetransmitter according to the embodiments is capable of wired/wirelesscommunication with the reception device (or the receiver) over a networkof 4G, 5G, 6G, etc. In addition, the transmitter may perform necessarydata processing operation according to the network system (e.g., a 4G,5G or 6G communication network system). The transmission device maytransmit the encapsulated data in an on-demand manner.

A point cloud data reception device 10005 according to the embodimentsmay include a receiver 10006, a file/segment decapsulation module 10007,a point cloud video decoder 10008, and/or a renderer 10009. According toembodiments, the reception device may include a device robot, a vehicle,AR/VR/XR devices, a portable device, a home appliance, an Internet ofThing (IoT) device, and an AI device/server which are configured toperform communication with a base station and/or other wireless devicesusing a radio access technology (e.g., 5G New RAT (NR), Long TermEvolution (LTE)).

The receiver 10006 according to the embodiments receives a bitstreamcontaining point cloud video data. According to embodiments, thereceiver 10006 may transmit feedback information to the point cloud datatransmission device 10000.

The file/segment decapsulation module 10007 decapsulates a file and/or asegment containing point cloud data. The decapsulation module accordingto the embodiments may perform a reverse process of the encapsulationprocess according to the embodiments.

The point cloud video decoder 10007 decodes the received point cloudvideo data. The decoder according to the embodiments may perform areverse process of encoding according to the embodiments.

The renderer 10009 renders the decoded point cloud video data. Accordingto embodiments, the renderer 10009 may transmit the feedback informationobtained at the reception side to the point cloud video decoder 10008.The point cloud video data according to the embodiments may carryfeedback information to the receiver. According to embodiments, thefeedback information received by the point cloud transmission device maybe provided to the point cloud video encoder.

The arrows indicated by dotted lines in the drawing represent atransmission path of feedback information acquired by the receptiondevice 10005. The feedback information is information for reflectinginteractivity with a user who consumes point cloud content, and includesuser information (e.g., head orientation information), viewportinformation, and the like). In particular, when the point cloud contentis content for a service (e.g., autonomous driving service, etc.) thatrequires interaction with a user, the feedback information may beprovided to the content transmitting side (e.g., the transmission device10000) and/or the service provider. According to embodiments, thefeedback information may be used in the reception device 10005 as wellas the transmission device 10000, and may not be provided.

The head orientation information according to embodiments is informationabout a user's head position, orientation, angle, motion, and the like.The reception device 10005 according to the embodiments may calculateviewport information based on the head orientation information. Theviewport information may be information about a region of the pointcloud video that the user is viewing. A viewpoint is a point where auser is viewing a point cloud video, and may refer to a center point ofthe viewport region. That is, the viewport is a region centered on theviewpoint, and the size and shape of the region may be determined by afield of view (FOV). Accordingly, the reception device 10005 may extractthe viewport information based on a vertical or horizontal FOV supportedby the device in addition to the head orientation information. Inaddition, the reception device 10005 performs gaze analysis to check howthe user consumes a point cloud, a region that the user gazes at in thepoint cloud video, a gaze time, and the like. According to embodiments,the reception device 10005 may transmit feedback information includingthe result of the gaze analysis to the transmission device 10000. Thefeedback information according to the embodiments may be acquired in therendering and/or display process. The feedback information according tothe embodiments may be secured by one or more sensors included in thereception device 10005. In addition, according to embodiments, thefeedback information may be secured by the renderer 10009 or a separateexternal element (or device, component, etc.). The dotted lines in FIG.1 represent a process of transmitting the feedback information securedby the renderer 10009. The point cloud content providing system mayprocess (encode/decode) point cloud data based on the feedbackinformation. Accordingly, the point cloud video data decoder 10008 mayperform a decoding operation based on the feedback information. Thereception device 10005 may transmit the feedback information to thetransmission device. The transmission device (or the point cloud videodata encoder 10002) may perform an encoding operation based on thefeedback information. Accordingly, the point cloud content providingsystem may efficiently process necessary data (e.g., point cloud datacorresponding to the user's head position) based on the feedbackinformation rather than processing (encoding/decoding) all point clouddata, and provide point cloud content to the user.

According to embodiments, the transmission device 10000 may be called anencoder, a transmission device, a transmitter, or the like, and thereception device 10004 may be called a decoder, a reception device, areceiver, or the like.

The point cloud data processed in the point cloud content providingsystem of FIG. 1 according to embodiments (through a series of processesof acquisition/encoding/transmission/decoding/rendering) may be referredto as point cloud content data or point cloud video data. According toembodiments, the point cloud content data may be used as a conceptcovering metadata or signaling information related to point cloud data.

The elements of the point cloud content providing system illustrated inFIG. 1 may be implemented by hardware, software, a processor, and/orcombinations thereof.

Embodiments may provide a method of providing point cloud content toprovide a user with various services such as virtual reality (VR),augmented reality (AR), mixed reality (MR), and autonomous driving.

In order to provide a point cloud content service, a point cloud videomay be acquired first. The acquired point cloud video may be transmittedthrough a series of processes, and the reception side may process thereceived data back into the original point cloud video and render theprocessed point cloud video. Thereby, the point cloud video may beprovided to the user. Embodiments provide a method of effectivelyperforming this series of processes.

The entire processes for providing a point cloud content service (thepoint cloud data transmission method and/or point cloud data receptionmethod) may include an acquisition process, an encoding process, atransmission process, a decoding process, a rendering process, and/or afeedback process.

According to embodiments, the process of providing point cloud content(or point cloud data) may be referred to as a point cloud compressionprocess. According to embodiments, the point cloud compression processmay represent a geometry-based point cloud compression process.

Each element of the point cloud data transmission device and the pointcloud data reception device according to the embodiments may behardware, software, a processor, and/or a combination thereof.

In order to provide a point cloud content service, a point cloud videomay be acquired. The acquired point cloud video is transmitted through aseries of processes, and the reception side may process the receiveddata back into the original point cloud video and render the processedpoint cloud video. Thereby, the point cloud video may be provided to theuser. Embodiments provide a method of effectively performing this seriesof processes.

The entire processes for providing a point cloud content service mayinclude an acquisition process, an encoding process, a transmissionprocess, a decoding process, a rendering process, and/or a feedbackprocess.

The point cloud compression system may include a transmission device anda reception device. The transmission device may output a bitstream byencoding a point cloud video, and deliver the same to the receptiondevice through a digital storage medium or a network in the form of afile or a stream (streaming segment). The digital storage medium mayinclude various storage media such as a USB, SD, CD, DVD, Blu-ray, HDD,and SSD.

The transmission device may include a point cloud video acquirer, apoint cloud video encoder, a file/segment encapsulator, and atransmitter. The reception device may include a receiver, a file/segmentdecapsulator, a point cloud video decoder, and a renderer. The encodermay be referred to as a point cloud video/picture/picture/frame encoder,and the decoder may be referred to as a point cloudvideo/picture/picture/frame decoding device. The transmitter may beincluded in the point cloud video encoder. The receiver may be includedin the point cloud video decoder. The renderer may include a display.The renderer and/or the display may be configured as separate devices orexternal components. The transmission device and the reception devicemay further include a separate internal or externalmodule/unit/component for the feedback process.

According to embodiments, the operation of the reception device may bethe reverse process of the operation of the transmission device.

The point cloud video acquirer may perform the process of acquiringpoint cloud video through a process of capturing, composing, orgenerating point cloud video. In the acquisition process, data of 3Dpositions (x, y, z)/attributes (color, reflectance, transparency, etc.)of multiple points, for example, a polygon file format (PLY) (or theStanford Triangle format) file may be generated. For a video havingmultiple frames, one or more files may be acquired. During the captureprocess, point cloud related metadata (e.g., capture related metadata)may be generated.

A point cloud data transmission device according to embodiments mayinclude an encoder configured to encode point cloud data, and atransmitter configured to transmit the point cloud data. The data may betransmitted in the form of a bitstream containing a point cloud.

A point cloud data reception device according to embodiments may includea receiver configured to receive point cloud data, a decoder configuredto decode the point cloud data, and a renderer configured to render thepoint cloud data.

The method/device according to the embodiments represents the pointcloud data transmission device and/or the point cloud data receptiondevice.

FIG. 2 illustrates capture of point cloud data according to embodiments.

Point cloud data according to embodiments may be acquired by a camera orthe like. A capturing technique according to embodiments may include,for example, inward-facing and/or outward-facing.

In the inward-facing according to the embodiments, one or more camerasinwardly facing an object of point cloud data may photograph the objectfrom the outside of the object.

In the outward-facing according to the embodiments, one or more camerasoutwardly facing an object of point cloud data may photograph theobject. For example, according to embodiments, there may be fourcameras.

The point cloud data or the point cloud content according to theembodiments may be a video or a still image of an object/environmentrepresented in various types of 3D spaces. According to embodiments, thepoint cloud content may include video/audio/an image of an object.

For capture of point cloud content, a combination of camera equipment (acombination of an infrared pattern projector and an infrared camera)capable of acquiring depth and RGB cameras capable of extracting colorinformation corresponding to the depth information may be configured.Alternatively, the depth information may be extracted through LiDAR,which uses a radar system that measures the location coordinates of areflector by emitting a laser pulse and measuring the return time. Ashape of the geometry consisting of points in a 3D space may beextracted from the depth information, and an attribute representing thecolor/reflectance of each point may be extracted from the RGBinformation. The point cloud content may include information about thepositions (x, y, z) and color (YCbCr or RGB) or reflectance (r) of thepoints. For the point cloud content, the outward-facing technique ofcapturing an external environment and the inward-facing technique ofcapturing a central object may be used. In the VR/AR environment, whenan object (e.g., a core object such as a character, a player, a thing,or an actor) is configured into point cloud content that may be viewedby the user in any direction (360 degrees), the configuration of thecapture camera may be based on the inward-facing technique. When thecurrent surrounding environment is configured into point cloud contentin a mode of a vehicle, such as autonomous driving, the configuration ofthe capture camera may be based on the outward-facing technique. Becausethe point cloud content may be captured by multiple cameras, a cameracalibration process may need to be performed before the content iscaptured to configure a global coordinate system for the cameras.

The point cloud content may be a video or still image of anobject/environment presented in various types of 3D spaces.

Additionally, in the point cloud content acquisition method, any pointcloud video may be composed based on the captured point cloud video.Alternatively, when a point cloud video for a computer-generated virtualspace is to be provided, capturing with an actual camera may not beperformed. In this case, the capture process may be replaced simply by aprocess of generating related data.

Post-processing may be needed for the captured point cloud video toimprove the quality of the content. In the video capture process, themaximum/minimum depth may be adjusted within a range provided by thecamera equipment. Even after the adjustment, point data of an unwantedarea may still be present. Accordingly, post-processing of removing theunwanted area (e.g., the background) or recognizing a connected spaceand filling the spatial holes may be performed. In addition, pointclouds extracted from the cameras sharing a spatial coordinate systemmay be integrated into one piece of content through the process oftransforming each point into a global coordinate system based on thecoordinates of the location of each camera acquired through acalibration process. Thereby, one piece of point cloud content having awide range may be generated, or point cloud content with a high densityof points may be acquired.

The point cloud video encoder may encode the input point cloud videointo one or more video streams. One video may include a plurality offrames, each of which may correspond to a still image/picture. In thisspecification, a point cloud video may include a point cloudimage/frame/picture/video/audio. In addition, the term “point cloudvideo” may be used interchangeably with a point cloudimage/frame/picture. The point cloud video encoder may perform avideo-based point cloud compression (V-PCC) procedure. The point cloudvideo encoder may perform a series of procedures such as prediction,transformation, quantization, and entropy coding for compression andencoding efficiency. The encoded data (encoded video/image information)may be output in the form of a bitstream. Based on the V-PCC procedure,the point cloud video encoder may encode point cloud video by dividingthe same into a geometry video, an attribute video, an occupancy mapvideo, and auxiliary information, which will be described later. Thegeometry video may include a geometry image, the attribute video mayinclude an attribute image, and the occupancy map video may include anoccupancy map image. The auxiliary information may include auxiliarypatch information. The attribute video/image may include a texturevideo/image.

The encapsulation processor (file/segment encapsulation module) 1003 mayencapsulate the encoded point cloud video data and/or metadata relatedto the point cloud video in the form of, for example, a file. Here, themetadata related to the point cloud video may be received from themetadata processor. The metadata processor may be included in the pointcloud video encoder or may be configured as a separate component/module.The encapsulation processor may encapsulate the data in a file formatsuch as ISOBMFF or process the same in the form of a DASH segment or thelike. According to an embodiment, the encapsulation processor mayinclude the point cloud video-related metadata in the file format. Thepoint cloud video metadata may be included, for example, in boxes atvarious levels on the ISOBMFF file format or as data in a separate trackwithin the file. According to an embodiment, the encapsulation processormay encapsulate the point cloud video-related metadata into a file. Thetransmission processor may perform processing for transmission on thepoint cloud video data encapsulated according to the file format. Thetransmission processor may be included in the transmitter or may beconfigured as a separate component/module. The transmission processormay process the point cloud video data according to a transmissionprotocol. The processing for transmission may include processing fordelivery over a broadcast network and processing for delivery through abroadband. According to an embodiment, the transmission processor mayreceive point cloud video-related metadata from the metadata processoralong with the point cloud video data, and perform processing of thepoint cloud video data for transmission.

The transmitter 1004 may transmit the encoded video/image information ordata that is output in the form of a bitstream to the receiver of thereception device through a digital storage medium or a network in theform of a file or streaming. The digital storage medium may includevarious storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.The transmitter may include an element for generating a media file in apredetermined file format, and may include an element for transmissionover a broadcast/communication network. The receiver may extract thebitstream and transmit the extracted bitstream to the decoding device.

The receiver 1003 may receive point cloud video data transmitted by thepoint cloud video transmission device according to the presentdisclosure. Depending on the transmission channel, the receiver mayreceive the point cloud video data over a broadcast network or through abroadband. Alternatively, the point cloud video data may be receivedthrough a digital storage medium.

The reception processor may process the received point cloud video dataaccording to the transmission protocol. The reception processor may beincluded in the receiver or may be configured as a separatecomponent/module. The reception processor may reversely perform theabove-described process of the transmission processor such that theprocessing corresponds to the processing for transmission performed atthe transmission side. The reception processor may deliver the acquiredpoint cloud video data to the decapsulation processor, and the acquiredpoint cloud video-related metadata to the metadata parser. The pointcloud video-related metadata acquired by the reception processor maytake the form of a signaling table.

The decapsulation processor (file/segment decapsulation module) 10007may decapsulate the point cloud video data received in the form of afile from the reception processor. The decapsulation processor maydecapsulate the files according to ISOBMFF or the like, and may acquirea point cloud video bitstream or point cloud video-related metadata (ametadata bitstream). The acquired point cloud video bitstream may bedelivered to the point cloud video decoder, and the acquired point cloudvideo-related metadata (metadata bitstream) may be delivered to themetadata processor. The point cloud video bitstream may include themetadata (metadata bitstream). The metadata processor may be included inthe point cloud video decoder or may be configured as a separatecomponent/module. The point cloud video-related metadata acquired by thedecapsulation processor may take the form of a box or a track in thefile format. The decapsulation processor may receive metadata necessaryfor decapsulation from the metadata processor, when necessary. The pointcloud video-related metadata may be delivered to the point cloud videodecoder and used in a point cloud video decoding procedure, or may betransferred to the renderer and used in a point cloud video renderingprocedure.

The point cloud video decoder may receive the bitstream and decode thevideo/image by performing an operation corresponding to the operation ofthe point cloud video encoder. In this case, the point cloud videodecoder may decode the point cloud video by dividing the same into ageometry video, an attribute video, an occupancy map video, andauxiliary information as described below. The geometry video may includea geometry image, and the attribute video may include an attributeimage. The occupancy map video may include an occupancy map image. Theauxiliary information may include auxiliary patch information. Theattribute video/image may include a texture video/image.

The 3D geometry may be reconstructed based on the decoded geometryimage, the occupancy map, and auxiliary patch information, and then maybe subjected to a smoothing process. A color point cloud image/picturemay be reconstructed by assigning color values to the smoothed 3Dgeometry based on the texture image. The renderer may render thereconstructed geometry and the color point cloud image/picture. Therendered video/image may be displayed through the display. The user mayview all or part of the rendered result through a VR/AR display or atypical display.

The feedback process may include transferring various kinds of feedbackinformation that may be acquired in the rendering/displaying process tothe transmission side or to the decoder of the reception side.Interactivity may be provided through the feedback process in consumingpoint cloud video. According to an embodiment, head orientationinformation, viewport information indicating a region currently viewedby a user, and the like may be delivered to the transmission side in thefeedback process. According to an embodiment, the user may interact withthings implemented in the VR/AR/MR/autonomous driving environment. Inthis case, information related to the interaction may be delivered tothe transmission side or a service provider during the feedback process.According to an embodiment, the feedback process may be skipped.

The head orientation information may represent information about thelocation, angle and motion of a user's head. On the basis of thisinformation, information about a region of the point cloud videocurrently viewed by the user, that is, viewport information, may becalculated.

The viewport information may be information about a region of the pointcloud video currently viewed by the user. Gaze analysis may be performedusing the viewport information to check the way the user consumes thepoint cloud video, a region of the point cloud video at which the usergazes, and how long the user gazes at the region. The gaze analysis maybe performed at the reception side and the result of the analysis may bedelivered to the transmission side on a feedback channel. A device suchas a VR/AR/MR display may extract a viewport region based on thelocation/direction of the user's head, vertical or horizontal FOVsupported by the device, and the like.

According to an embodiment, the aforementioned feedback information maynot only be delivered to the transmission side, but also be consumed atthe reception side. That is, decoding and rendering processes at thereception side may be performed based on the aforementioned feedbackinformation. For example, only the point cloud video for the regioncurrently viewed by the user may be preferentially decoded and renderedbased on the head orientation information and/or the viewportinformation.

Here, the viewport or viewport region may represent a region of thepoint cloud video currently viewed by the user. A viewpoint is a pointwhich is viewed by the user in the point cloud video and may represent acenter point of the viewport region. That is, a viewport is a regionaround a viewpoint, and the size and form of the region may bedetermined by the field of view (FOV).

The present disclosure relates to point cloud video compression asdescribed above. For example, the methods/embodiments disclosed in thepresent disclosure may be applied to the point cloud compression orpoint cloud coding (PCC) standard of the moving picture experts group(MPEG) or the next generation video/image coding standard.

As used herein, a picture/frame may generally represent a unitrepresenting one image in a specific time interval.

A pixel or a pel may be the smallest unit constituting one picture (orimage). Also, “sample” may be used as a term corresponding to a pixel. Asample may generally represent a pixel or a pixel value. It mayrepresent only a pixel/pixel value of a luma component, only apixel/pixel value of a chroma component, or only a pixel/pixel value ofa depth component.

A unit may represent a basic unit of image processing. The unit mayinclude at least one of a specific region of the picture and informationrelated to the region. The unit may be used interchangeably with termsuch as block or area in some cases. In a general case, an M×N block mayinclude samples (or a sample array) or a set (or array) of transformcoefficients configured in M columns and N rows.

FIG. 3 illustrates an example of a point cloud, a geometry image, and atexture image according to embodiments.

A point cloud according to the embodiments may be input to the V-PCCencoding process of FIG. 4, which will be described later, to generate ageometric image and a texture image. According to embodiments, a pointcloud may have the same meaning as point cloud data.

As shown in the figure, the left part shows a point cloud, in which anobject is positioned in a 3D space and may be represented by a boundingbox or the like. The middle part shows the geometry, and the right partshows a texture image (non-padded image).

Video-based point cloud compression (V-PCC) according to embodiments mayprovide a method of compressing 3D point cloud data based on a 2D videocodec such as HEVC or VVC. Data and information that may be generated inthe V-PCC compression process are as follows:

Occupancy map: this is a binary map indicating whether there is data ata corresponding position in a 2D plane, using a value of 0 or 1 individing the points constituting a point cloud into patches and mappingthe same to the 2D plane. The occupancy map may represent a 2D arraycorresponding to ATLAS, and the values of the occupancy map may indicatewhether each sample position in the atlas corresponds to a 3D point.

An atlas is a collection of 2D bounding boxes positioned in arectangular frame that correspond to a 3D bounding box in a 3D space inwhich volumetric data is rendered and information related thereto.

The atlas bitstream is a bitstream for one or more atlas framesconstituting an atlas and related data.

The atlas frame is a 2D rectangular array of atlas samples onto whichpatches are projected.

An atlas sample is a position of a rectangular frame onto which patchesassociated with the atlas are projected.

An atlas frame may be partitioned into tiles. A tile is a unit in whicha 2D frame is partitioned. That is, a tile is a unit for partitioningsignaling information of point cloud data called an atlas.

Patch: A set of points constituting a point cloud, which indicates thatpoints belonging to the same patch are adjacent to each other in 3Dspace and are mapped in the same direction among 6-face bounding boxplanes in the process of mapping to a 2D image.

A patch is a unit in which a tile partitioned. The patch is signalinginformation on the configuration of point cloud data.

The reception device according to the embodiments may restore attributevideo data, geometry video data, and occupancy video data, which areactual video data having the same presentation time, based on an atlas(tile, patch).

Geometry image: this is an image in the form of a depth map thatpresents position information (geometry) about each point constituting apoint cloud on a patch-by-patch basis. The geometry image may becomposed of pixel values of one channel. Geometry represents a set ofcoordinates associated with a point cloud frame.

Texture image: this is an image representing the color information abouteach point constituting a point cloud on a patch-by-patch basis. Atexture image may be composed of pixel values of a plurality of channels(e.g., three channels of R, G, and B). The texture is included in anattribute. According to embodiments, a texture and/or attribute may beinterpreted as the same object and/or having an inclusive relationship.

Auxiliary patch info: this indicates metadata needed to reconstruct apoint cloud with individual patches. Auxiliary patch info may includeinformation about the position, size, and the like of a patch in a 2D/3Dspace.

Point cloud data according to the embodiments, for example, V-PCCcomponents may include an atlas, an occupancy map, geometry, andattributes.

Atlas represents a set of 2D bounding boxes. It may be patches, forexample, patches projected onto a rectangular frame. Atlas maycorrespond to a 3D bounding box in a 3D space, and may represent asubset of a point cloud.

An attribute may represent a scalar or vector associated with each pointin the point cloud. For example, the attributes may include color,reflectance, surface normal, time stamps, material ID.

The point cloud data according to the embodiments represents PCC dataaccording to video-based point cloud compression (V-PCC) scheme. Thepoint cloud data may include a plurality of components. For example, itmay include an occupancy map, a patch, geometry and/or texture.

FIG. 4 illustrates a V-PCC encoding process according to embodiments.

The figure illustrates a V-PCC encoding process for generating andcompressing an occupancy map, a geometry image, a texture image, andauxiliary patch information. The V-PCC encoding process of FIG. 4 may beprocessed by the point cloud video encoder 10002 of FIG. 1. Each elementof FIG. 4 may be performed by software, hardware, processor and/or acombination thereof.

The patch generation or patch generator 40000 receives a point cloudframe (which may be in the form of a bitstream containing point clouddata). The patch generator 40000 generates a patch from the point clouddata. In addition, patch information including information about patchgeneration is generated.

The patch packing or patch packer 40001 packs patches for point clouddata. For example, one or more patches may be packed. In addition, thepatch packer generates an occupancy map containing information aboutpatch packing.

The geometry image generation or geometry image generator 40002generates a geometry image based on the point cloud data, patches,and/or packed patches. The geometry image refers to data containinggeometry related to the point cloud data.

The texture image generation or texture image generator 40003 generatesa texture image based on the point cloud data, patches, and/or packedpatches. In addition, the texture image may be generated further basedon smoothed geometry generated by smoothing processing of smoothingbased on the patch information.

The smoothing or smoother 40004 may mitigate or eliminate errorscontained in the image data. For example, based on the patchedreconstructed geometry image, portions that may cause errors betweendata may be smoothly filtered out to generate smoothed geometry.

The auxiliary patch info compression or auxiliary patch info compressor40005, auxiliary patch information related to the patch informationgenerated in the patch generation is compressed. In addition, thecompressed auxiliary patch information may be transmitted to themultiplexer. The auxiliary patch information may be used in the geometryimage generation 40002.

The image padding or image padder 40006, 40007 may pad the geometryimage and the texture image, respectively. The padding data may bepadded to the geometry image and the texture image.

The group dilation or group dilator 40008 may add data to the textureimage in a similar manner to image padding. The added data may beinserted into the texture image.

The video compression or video compressor 40009, 40010, 40011 maycompress the padded geometry image, the padded texture image, and/or theoccupancy map, respectively. The compression may encode geometryinformation, texture information, occupancy information, and the like.

The entropy compression or entropy compressor 40012 may compress (e.g.,encode) the occupancy map based on an entropy scheme.

According to embodiments, the entropy compression and/or videocompression may be performed, respectively depending on whether thepoint cloud data is lossless and/or lossy.

The multiplexer 40013 multiplexes the compressed geometry image, thecompressed texture image, and the compressed occupancy map into abitstream.

The specific operations in the respective processes of FIG. 4 aredescribed below.

Patch Generation 40000

The patch generation process refers to a process of dividing a pointcloud into patches, which are mapping units, in order to map the pointcloud to the 2D image. The patch generation process may be divided intothree steps: normal value calculation, segmentation, and patchsegmentation.

The normal value calculation process will be described in detail withreference to FIG. 5.

FIG. 5 illustrates an example of a tangent plane and a normal vector ofa surface according to embodiments.

The surface of FIG. 5 is used in the patch generation process 40000 ofthe V-PCC encoding process of FIG. 4 as follows.

Normal calculation related to patch generation:

Each point of a point cloud has its own direction, which is representedby a 3D vector called a normal vector. Using the neighbors of each pointobtained using a K-D tree or the like, a tangent plane and a normalvector of each point constituting the surface of the point cloud asshown in the figure may be obtained. The search range applied to theprocess of searching for neighbors may be defined by the user.

The tangent plane refers to a plane that passes through a point on thesurface and completely includes a tangent line to the curve on thesurface.

FIG. 6 illustrates an exemplary bounding box of a point cloud accordingto embodiments.

A method/device according to embodiments, for example, patch generation,may employ a bounding box in generating a patch from point cloud data.

The bounding box according to the embodiments refers to a box of a unitfor dividing point cloud data based on a hexahedron in a 3D space.

The bounding box may be used in the process of projecting a targetobject of the point cloud data onto a plane of each planar face of ahexahedron in a 3D space. The bounding box may be generated andprocessed by the point cloud video acquirer 10000 and the point cloudvideo encoder 10002 of FIG. 1. Further, based on the bounding box, thepatch generation 40000, patch packing 40001, geometry image generation40002, and texture image generation 40003 of the V-PCC encoding processof FIG. 2 may be performed.

Segmentation Related to Patch Generation

Segmentation is divided into two processes: initial segmentation andrefine segmentation.

The point cloud encoder 10002 according to the embodiments projects apoint onto one face of a bounding box. Specifically, each pointconstituting a point cloud is projected onto one of the six faces of abounding box surrounding the point cloud as shown in the figure. Initialsegmentation is a process of determining one of the planar faces of thebounding box onto which each point is to be projected.

{right arrow over (n)}_(Pidx), which is a normal value corresponding toeach of the six planar faces, is defined as follows:

(1.0, 0.0, 0.0), (0.0, 1.0, 0.0), (0.0, 0.0, 1.0), (−1.0, 0.0, 0.0),(0.0, −1.0, 0.0), (0.0, 0.0, −1.0).

As shown in the equation below, a face that yields the maximum value ofdot product of the normal vector {right arrow over (n)}_(Pi) of eachpoint, which is obtained in the normal value calculation process, and{right arrow over (n)}_(Pidx) is determined as a projection plane of thecorresponding point. That is, a plane whose normal vector is mostsimilar to the direction of the normal vector of a point is determinedas the projection plane of the point.

$\max\limits_{p_{i\; d\; x}}\left\{ {{\overset{\rightarrow}{n}}_{p_{i}} \cdot {\overset{\rightarrow}{n}}_{p_{i\; d\; x}}} \right\}$

The determined plane may be identified by one cluster index, which isone of 0 to 5.

Refine segmentation is a process of enhancing the projection plane ofeach point constituting the point cloud determined in the initialsegmentation process in consideration of the projection planes ofneighboring points. In this process, a score normal, which representsthe degree of similarity between the normal vector of each point and thenormal of each planar face of the bounding box which are considered indetermining the projection plane in the initial segmentation process,and score smooth, which indicates the degree of similarity between theprojection plane of the current point and the projection planes ofneighboring points, may be considered together.

Score smooth may be considered by assigning a weight to the scorenormal. In this case, the weight value may be defined by the user. Therefine segmentation may be performed repeatedly, and the number ofrepetitions may also be defined by the user.

Patch Segmentation Related to Patch Generation

Patch segmentation is a process of dividing the entire point cloud intopatches, which are sets of neighboring points, based on the projectionplane information about each point constituting the point cloud obtainedin the initial/refine segmentation process. The patch segmentation mayinclude the following steps:

1) Calculate neighboring points of each point constituting the pointcloud, using the K-D tree or the like. The maximum number of neighborsmay be defined by the user;

2) When the neighboring points are projected onto the same plane as thecurrent point (when they have the same cluster index), extract thecurrent point and the neighboring points as one patch;

3) Calculate geometry values of the extracted patch. The details aredescribed below; and

4) Repeat operations 2) to 4) until there is no unextracted point.

The occupancy map, geometry image and texture image for each patch aswell as the size of each patch are determined through the patchsegmentation process.

FIG. 7 illustrates an example of determination of individual patchpositions on an occupancy map according to embodiments.

The point cloud encoder 10002 according to the embodiments may performpatch packing and generate an occupancy map.

Patch Packing & Occupancy Map Generation (40001)

This is a process of determining the positions of individual patches ina 2D image to map the segmented patches to the 2D image. The occupancymap, which is a kind of 2D image, is a binary map that indicates whetherthere is data at a corresponding position, using a value of 0 or 1. Theoccupancy map is composed of blocks and the resolution thereof may bedetermined by the size of the block. For example, when the block is 1*1block, a pixel-level resolution is obtained. The occupancy packing blocksize may be determined by the user.

The process of determining the positions of individual patches on theoccupancy map may be configured as follows:

1) Set all positions on the occupancy map to 0;

2) Place a patch at a point (u, v) having a horizontal coordinate withinthe range of (0, occupancySizeU−patch.sizeU0) and a vertical coordinatewithin the range of (0, occupancySizeV−patch.sizeV0) in the occupancymap plane;

3) Set a point (x, y) having a horizontal coordinate within the range of(0, patch.sizeU0) and a vertical coordinate within the range of (0,patch.sizeV0) in the patch plane as a current point;

4) Change the position of point (x, y) in raster order and repeatoperations 3) and 4) if the value of coordinate (x, y) on the patchoccupancy map is 1 (there is data at the point in the patch) and thevalue of coordinate (u+x, v+y) on the global occupancy map is 1 (theoccupancy map is filled with the previous patch). Otherwise, proceed tooperation 6);

5) Change the position of (u, v) in raster order and repeat operations3) to 5);

6) Determine (u, v) as the position of the patch and copy the occupancymap data about the patch onto the corresponding portion on the globaloccupancy map; and

7) Repeat operations 2) to 7) for the next patch.

occupancySizeU: indicates the width of the occupancy map. The unitthereof is occupancy packing block size.

occupancySizeV: indicates the height of the occupancy map. The unitthereof is occupancy packing block size.

patch.sizeU0: indicates the width of the occupancy map. The unit thereofis occupancy packing block size.

patch.sizeV0: indicates the height of the occupancy map. The unitthereof is occupancy packing block size.

For example, as shown in FIG. 7, there is a box corresponding to a patchhaving a patch size in a box corresponding to an occupancy packing sizeblock, and a point (x, y) may be located in the box.

FIG. 8 shows an exemplary relationship among normal, tangent, andbitangent axes according to embodiments.

The point cloud encoder 10002 according to embodiments may generate ageometry image. The geometry image refers to image data includinggeometry information about a point cloud. The geometry image generationprocess may employ three axes (normal, tangent, and bitangent) of apatch in FIG. 8.

Geometry Image Generation (40002)

In this process, the depth values constituting the geometry images ofindividual patches are determined, and the entire geometry image isgenerated based on the positions of the patches determined in the patchpacking process described above. The process of determining the depthvalues constituting the geometry images of individual patches may beconfigured as follows.

1) Calculate parameters related to the position and size of anindividual patch. The parameters may include the following information.

A normal index indicating the normal axis is obtained in the previouspatch generation process. The tangent axis is an axis coincident withthe horizontal axis u of the patch image among the axes perpendicular tothe normal axis, and the bitangent axis is an axis coincident with thevertical axis v of the patch image among the axes perpendicular to thenormal axis. The three axes may be expressed as shown in the figure.

FIG. 9 shows an exemplary configuration of the minimum mode and maximummode of a projection mode according to embodiments.

The point cloud encoder 10002 according to embodiments may performpatch-based projection to generate a geometry image, and the projectionmode according to the embodiments includes a minimum mode and a maximummode.

3D spatial coordinates of a patch may be calculated based on thebounding box of the minimum size surrounding the patch. For example, the3D spatial coordinates may include the minimum tangent value of thepatch (on the patch 3d shift tangent axis) of the patch, the minimumbitangent value of the patch (on the patch 3d shift bitangent axis), andthe minimum normal value of the patch (on the patch 3d shift normalaxis).

2D size of a patch indicates the horizontal and vertical sizes of thepatch when the patch is packed into a 2D image. The horizontal size(patch 2d size u) may be obtained as a difference between the maximumand minimum tangent values of the bounding box, and the vertical size(patch 2d size v) may be obtained as a difference between the maximumand minimum bitangent values of the bounding box.

2) Determine a projection mode of the patch. The projection mode may beeither the min mode or the max mode. The geometry information about thepatch is expressed with a depth value. When each point constituting thepatch is projected in the normal direction of the patch, two layers ofimages, an image constructed with the maximum depth value and an imageconstructed with the minimum depth value, may be generated.

In the min mode, in generating the two layers of images d0 and d1, theminimum depth may be configured for d0, and the maximum depth within thesurface thickness from the minimum depth may be configured for d1, asshown in the figure.

For example, when a point cloud is located in 2D as illustrated in thefigure, there may be a plurality of patches including a plurality ofpoints. As shown in the figure, it is indicated that points marked withthe same style of shadow may belong to the same patch. The figureillustrates the process of projecting a patch of points marked withblanks.

When projecting points marked with blanks to the left/right, the depthmay be incremented by 1 as 0, 1, 2, . . . , 6, 7, 8, 9 with respect tothe left side, and the number for calculating the depths of the pointsmay be marked on the right side.

The same projection mode may be applied to all point clouds or differentprojection modes may be applied to respective frames or patchesaccording to user definition. When different projection modes areapplied to the respective frames or patches, a projection mode that mayenhance compression efficiency or minimize missed points may beadaptively selected.

3) Calculate the depth values of the individual points.

In the min mode, image d0 is constructed with depth0, which is a valueobtained by subtracting the minimum normal value of the patch (on thepatch 3d shift normal axis) calculated in operation 1) from the minimumnormal value of the patch (on the patch 3d shift normal axis) for theminimum normal value of each point. If there is another depth valuewithin the range between depth0 and the surface thickness at the sameposition, this value is set to depth1. Otherwise, the value of depth0 isassigned to depth1. Image d1 is constructed with the value of depth1.

For example, a minimum value may be calculated in determining the depthof points of image d0 (4 2 4 4 0 6 0 0 9 9 0 8 0). In determining thedepth of points of image d1, a greater value among two or more pointsmay be calculated. When only one point is present, the value thereof maybe calculated (4 4 4 4 6 6 6 8 9 9 8 8 9). In the process of encodingand reconstructing the points of the patch, some points may be lost (Forexample, in the figure, eight points are lost).

In the max mode, image d0 is constructed with depth0, which is a valueobtained by subtracting the minimum normal value of the patch (on thepatch 3d shift normal axis) calculated in operation 1) from the minimumnormal value of the patch (on the patch 3d shift normal axis) for themaximum normal value of each point. If there is another depth valuewithin the range between depth0 and the surface thickness at the sameposition, this value is set to depth1. Otherwise, the value of depth0 isassigned to depth1. Image d1 is constructed with the value of depth1.

For example, a maximum value may be calculated in determining the depthof points of d0 (4 4 4 4 6 6 6 8 9 9 8 8 9). In addition, in determiningthe depth of points of d1, a lower value among two or more points may becalculated. When only one point is present, the value thereof may becalculated (4 2 4 4 5 6 0 6 9 9 0 8 0). In the process of encoding andreconstructing the points of the patch, some points may be lost (Forexample, in the figure, six points are lost).

The entire geometry image may be generated by placing the geometryimages of the individual patches generated through the above-describedprocesses onto the entire geometry image based on the patch positioninformation determined in the patch packing process.

Layer d1 of the generated entire geometry image may be encoded usingvarious methods. A first method (absolute d1 method) is to encode thedepth values of the previously generated image d1. A second method(differential method) is to encode a difference between the depth valuesof previously generated image d1 and the depth values of image d0.

In the encoding method using the depth values of the two layers, d0 andd1 as described above, if there is another point between the two depths,the geometry information about the point is lost in the encodingprocess, and therefore an enhanced-delta-depth (EDD) code may be usedfor lossless coding.

Hereinafter, the EDD code will be described in detail with reference toFIG. 10.

FIG. 10 illustrates an exemplary EDD code according to embodiments.

In some/all processes of the point cloud encoder 10002 and/or V-PCCencoding (e.g., video compression 40009), the geometry information aboutpoints may be encoded based on the EOD code.

As shown in the figure, the EDD code is used for binary encoding of thepositions of all points within the range of surface thickness includingd1. For example, in the figure, the points included in the second leftcolumn may be represented by an EDD code of 0b1001 (=9) because thepoints are present at the first and fourth positions over D0 and thesecond and third positions are empty. When the EDD code is encodedtogether with D0 and transmitted, a reception terminal may restore thegeometry information about all points without loss.

For example, when there is a point present above a reference point, thevalue is 1. When there is no point, the value is 0. Thus, the code maybe expressed based on 4 bits.

Smoothing (40004)

Smoothing is an operation for eliminating discontinuity that may occuron the patch boundary due to deterioration of the image qualityoccurring during the compression process. Smoothing may be performed bythe point cloud encoder or smoother:

1) Reconstruct the point cloud from the geometry image. This operationmay be the reverse of the geometry image generation described above. Forexample, the reverse process of encoding may be reconstructed;

2) Calculate neighboring points of each point constituting thereconstructed point cloud using the K-D tree or the like;

3) Determine whether each of the points is positioned on the patchboundary. For example, when there is a neighboring point having adifferent projection plane (cluster index) from the current point, itmay be determined that the point is positioned on the patch boundary;

4) If there is a point present on the patch boundary, move the point tothe center of mass of the neighboring points (positioned at the averagex, y, z coordinates of the neighboring points). That is, change thegeometry value. Otherwise, maintain the previous geometry value.

FIG. 11 illustrates an example of recoloring based on color values ofneighboring points according to embodiments.

The point cloud encoder or the texture image generator 40003 accordingto the embodiments may generate a texture image based on recoloring.

Texture Image Generation (40003)

The texture image generation process, which is similar to the geometryimage generation process described above, includes generating textureimages of individual patches and generating an entire texture image byarranging the texture images at determined positions. However, in theoperation of generating texture images of individual patches, an imagewith color values (e.g., R, G, and B values) of the points constitutinga point cloud corresponding to a position is generated in place of thedepth values for geometry generation.

In estimating a color value of each point constituting the point cloud,the geometry previously obtained through the smoothing process may beused. In the smoothed point cloud, the positions of some points may havebeen shifted from the original point cloud, and accordingly a recoloringprocess of finding colors suitable for the changed positions may berequired. Recoloring may be performed using the color values ofneighboring points. For example, as shown in the figure, a new colorvalue may be calculated in consideration of the color value of thenearest neighboring point and the color values of the neighboringpoints.

For example, referring to the figure, in the recoloring, a suitablecolor value for a changed position may be calculated based on theaverage of the attribute information about the closest original pointsto a point and/or the average of the attribute information about theclosest original positions to the point.

Texture images may also be generated in two layers of t0 and t1, likethe geometry images, which are generated in two layers of d0 and d1.

Auxiliary Patch Info Compression (40005)

The point cloud encoder or the auxiliary patch info compressor accordingto the embodiments may compress the auxiliary patch information(auxiliary information about the point cloud).

The auxiliary patch info compressor compresses the auxiliary patchinformation generated in the patch generation, patch packing, andgeometry generation processes described above. The auxiliary patchinformation may include the following parameters:

Index (cluster index) for identifying the projection plane (normalplane);

3D spatial position of a patch, i.e., the minimum tangent value of thepatch (on the patch 3d shift tangent axis), the minimum bitangent valueof the patch (on the patch 3d shift bitangent axis), and the minimumnormal value of the patch (on the patch 3d shift normal axis);

2D spatial position and size of the patch, i.e., the horizontal size(patch 2d size u), the vertical size (patch 2d size v), the minimumhorizontal value (patch 2d shift u), and the minimum vertical value(patch 2d shift u); and

Mapping information about each block and patch, i.e., a candidate index(when patches are disposed in order based on the 2D spatial position andsize information about the patches, multiple patches may be mapped toone block in an overlapping manner. In this case, the mapped patchesconstitute a candidate list, and the candidate index indicates theposition in sequential order of a patch whose data is present in theblock), and a local patch index (which is an index indicating one of thepatches present in the frame). Table X shows a pseudo code representingthe process of matching between blocks and patches based on thecandidate list and the local patch indexes.

The maximum number of candidate lists may be defined by a user.

TABLE 1-1 Pseudo code for mapping a block to a patch for( i = 0; i <BlockCount; i++ ) { if( candidatePatches[ i ].size( ) = = 1 ) {blockToPatch[ i ] = candidatePatches[ i ][ 0 ] } else { candidate_indexif( candidate_index = = max_candidate_count ) { blockToPatch[ i ] =local_patch_index } else { blockToPatch[ i ] = candidatePatches[ i ][candidate_index ] } } }

FIG. 12 illustrates push-pull background filling according toembodiments.

Image Padding and Group Dilation (40006, 40007, 40008)

The image padder according to the embodiments may fill the space exceptthe patch area with meaningless supplemental data based on the push-pullbackground filling technique.

Image padding is a process of filling the space other than the patchregion with meaningless data to improve compression efficiency. Forimage padding, pixel values in columns or rows close to a boundary inthe patch may be copied to fill the empty space. Alternatively, as shownin the figure, a push-pull background filling method may be used.According to this method, the empty space is filled with pixel valuesfrom a low resolution image in the process of gradually reducing theresolution of a non-padded image and increasing the resolution again.

Group dilation is a process of filling the empty spaces of a geometryimage and a texture image configured in two layers, d0/d1 and t0/t1,respectively. In this process, the empty spaces of the two layerscalculated through image padding are filled with the average of thevalues for the same position.

FIG. 13 shows an exemplary possible traversal order for a 4*4 blockaccording to embodiments.

Occupancy Map Compression (40012, 40011)

The occupancy map compressor according to the embodiments may compressthe previously generated occupancy map. Specifically, two methods,namely video compression for lossy compression and entropy compressionfor lossless compression, may be used. Video compression is describedbelow.

The entropy compression may be performed through the followingoperations.

1) If a block constituting an occupancy map is fully occupied, encode 1and repeat the same operation for the next block of the occupancy map.Otherwise, encode 0 and perform operations 2) to 5).

2) Determine the best traversal order to perform run-length coding onthe occupied pixels of the block. The figure shows four possibletraversal orders for a 4*4 block.

FIG. 14 illustrates an exemplary best traversal order according toembodiments.

As described above, the entropy compressor according to the embodimentsmay code (encode) a block based on the traversal order scheme asdescribed above.

For example, the best traversal order with the minimum number of runs isselected from among the possible traversal orders and the index thereofis encoded. The figure illustrates a case where the third traversalorder in FIG. 13 is selected. In the illustrated case, the number ofruns may be minimized to 2, and therefore the third traversal order maybe selected as the best traversal order.

3) Encode the number of runs. In the example of FIG. 14, there are tworuns, and therefore 2 is encoded.

4) Encode the occupancy of the first run. In the example of FIG. 14, 0is encoded because the first run corresponds to unoccupied pixels.

5) Encode lengths of the individual runs (as many as the number ofruns). In the example of FIG. 14, the lengths of the first run and thesecond run, 6 and 10, are sequentially encoded.

Video Compression (40009, 40010, 40011)

The video compressor according to the embodiments encodes a sequence ofa geometry image, a texture image, an occupancy map image, and the likegenerated in the above-described operations, using a 2D video codec suchas HEVC or VVC.

FIG. 15 illustrates an exemplary 2D video/image encoder according toembodiments.

The figure, which represents an embodiment to which the videocompression or video compressor 40009, 40010, and 40011 described aboveis applied, is a schematic block diagram of a 2D video/image encoder15000 configured to encode a video/image signal. The 2D video/imageencoder 15000 may be included in the point cloud video encoder describedabove or may be configured as an internal/external component. Eachcomponent of FIG. 15 may correspond to software, hardware, processorand/or a combination thereof.

Here, the input image may include the geometry image, the texture image(attribute(s) image), and the occupancy map image described above. Theoutput bitstream (i.e., the point cloud video/image bitstream) of thepoint cloud video encoder may include output bitstreams for therespective input images (i.e., the geometry image, the texture image(attribute(s) image), the occupancy map image, etc.).

An inter-predictor 15090 and an intra-predictor 15100 may becollectively called a predictor. That is, the predictor may include theinter-predictor 15090 and the intra-predictor 15100. A transformer15030, a quantizer 15040, an inverse quantizer 15050, and an inversetransformer 15060 may be included in the residual processor. Theresidual processor may further include a subtractor 15020. According toan embodiment, the image splitter 15010, the subtractor 15020, thetransformer 15030, the quantizer 15040, the inverse quantizer 15050, theinverse transformer 15060, the adder 155, the filter 15070, theinter-predictor 15090, the intra-predictor 15100, and the entropyencoder 15110 described above may be configured by one hardwarecomponent (e.g., an encoder or a processor). In addition, the memory15080 may include a decoded picture buffer (DPB) and may be configuredby a digital storage medium.

The image splitter 15010 may spit an image (or a picture or a frame)input to the encoder 15000 into one or more processing units. Forexample, the processing unit may be called a coding unit (CU). In thiscase, the CU may be recursively split from a coding tree unit (CTU) or alargest coding unit (LCU) according to a quad-tree binary-tree (QTBT)structure. For example, one CU may be split into a plurality of CUs of alower depth based on a quad-tree structure and/or a binary-treestructure. In this case, for example, the quad-tree structure may beapplied first and the binary-tree structure may be applied later.Alternatively, the binary-tree structure may be applied first. Thecoding procedure according to the present disclosure may be performedbased on a final CU that is not split anymore. In this case, the LCU maybe used as the final CU based on coding efficiency according tocharacteristics of the image. When necessary, a CU may be recursivelysplit into CUs of a lower depth, and a CU of the optimum size may beused as the final CU. Here, the coding procedure may include prediction,transformation, and reconstruction, which will be described later. Asanother example, the processing unit may further include a predictionunit (PU) or a transform unit (TU). In this case, the PU and the TU maybe split or partitioned from the aforementioned final CU. The PU may bea unit of sample prediction, and the TU may be a unit for deriving atransform coefficient and/or a unit for deriving a residual signal fromthe transform coefficient.

The term “unit” may be used interchangeably with terms such as block orarea. In a general case, an M×N block may represent a set of samples ortransform coefficients configured in M columns and N rows. A sample maygenerally represent a pixel or a value of a pixel, and may indicate onlya pixel/pixel value of a luma component, or only a pixel/pixel value ofa chroma component. “Sample” may be used as a term corresponding to apixel or a pel in one picture (or image).

The encoder 15000 may generate a residual signal (residual block orresidual sample array) by subtracting a prediction signal (predictedblock or predicted sample array) output from the inter-predictor 15090or the intra-predictor 15100 from an input image signal (original blockor original sample array), and the generated residual signal istransmitted to the transformer 15030. In this case, as shown in thefigure, the unit that subtracts the prediction signal (predicted blockor predicted sample array) from the input image signal (original blockor original sample array) in the encoder 15000 may be called asubtractor 15020. The predictor may perform prediction for a processingtarget block (hereinafter referred to as a current block) and generate apredicted block including prediction samples for the current block. Thepredictor may determine whether intra-prediction or inter-prediction isapplied on a current block or CU basis. As will be described later inthe description of each prediction mode, the predictor may generatevarious kinds of information about prediction, such as prediction modeinformation, and deliver the generated information to the entropyencoder 15110. The information about the prediction may be encoded andoutput in the form of a bitstream by the entropy encoder 15110.

The intra-predictor 15100 may predict the current block with referenceto the samples in the current picture. The samples may be positioned inthe neighbor of or away from the current block depending on theprediction mode. In intra-prediction, the prediction modes may include aplurality of non-directional modes and a plurality of directional modes.The non-directional modes may include, for example, a DC mode and aplanar mode. The directional modes may include, for example, 33directional prediction modes or 65 directional prediction modesaccording to fineness of the prediction directions. However, this ismerely an example, and more or fewer directional prediction modes may beused depending on the setting. The intra-predictor 15100 may determine aprediction mode to be applied to the current block, based on theprediction mode applied to the neighboring block.

The inter-predictor 15090 may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on the reference picture. In this case, in order to reducethe amount of motion information transmitted in the inter-predictionmode, the motion information may be predicted on a per block, subblock,or sample basis based on the correlation in motion information betweenthe neighboring blocks and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include information about an inter-predictiondirection (L0 prediction, L1 prediction, Bi prediction, etc.). In thecase of inter-prediction, the neighboring blocks may include a spatialneighboring block, which is present in the current picture, and atemporal neighboring block, which is present in the reference picture.The reference picture including the reference block may be the same asor different from the reference picture including the temporalneighboring block. The temporal neighboring block may be referred to asa collocated reference block or a collocated CU (colCU), and thereference picture including the temporal neighboring block may bereferred to as a collocated picture (colPic). For example, theinter-predictor 15090 may configure a motion information candidate listbased on the neighboring blocks and generate information indicating acandidate to be used to derive a motion vector and/or a referencepicture index of the current block. Inter-prediction may be performedbased on various prediction modes. For example, in a skip mode and amerge mode, the inter-predictor 15090 may use motion information about aneighboring block as motion information about the current block. In theskip mode, unlike the merge mode, the residual signal may not betransmitted. In a motion vector prediction (MVP) mode, the motion vectorof a neighboring block may be used as a motion vector predictor and themotion vector difference may be signaled to indicate the motion vectorof the current block.

The prediction signal generated by the inter-predictor 15090 or theintra-predictor 15100 may be used to generate a reconstruction signal orto generate a residual signal.

The transformer 15030 may generate transform coefficients by applying atransformation technique to the residual signal. For example, thetransformation technique may include at least one of discrete cosinetransform (DCT), discrete sine transform (DST), Karhunen-Loéve transform(KLT), graph-based transform (GBT), or conditionally non-lineartransform (CNT). Here, the GBT refers to transformation obtained from agraph depicting the relationship between pixels. The CNT refers totransformation obtained based on a prediction signal generated based onall previously reconstructed pixels. In addition, the transformationoperation may be applied to pixel blocks having the same size of asquare, or may be applied to blocks of a variable size other than thesquare.

The quantizer 15040 may quantize the transform coefficients and transmitthe same to the entropy encoder 15110. The entropy encoder 15110 mayencode the quantized signal (information about the quantized transformcoefficients) and output a bitstream of the encoded signal. Theinformation about the quantized transform coefficients may be referredto as residual information. The quantizer 15040 may rearrange thequantized transform coefficients, which are in a block form, in the formof a one-dimensional vector based on a coefficient scan order, andgenerate information about the quantized transform coefficients based onthe quantized transform coefficients in the form of the one-dimensionalvector. The entropy encoder 15110 may employ various encoding techniquessuch as, for example, exponential Golomb, context-adaptive variablelength coding (CAVLC), and context-adaptive binary arithmetic coding(CABAC). The entropy encoder 15110 may encode information necessary forvideo/image reconstruction (e.g., values of syntax elements) togetherwith or separately from the quantized transform coefficients. Theencoded information (e.g., encoded video/image information) may betransmitted or stored in the form of a bitstream on a networkabstraction layer (NAL) unit basis. The bitstream may be transmittedover a network or may be stored in a digital storage medium. Here, thenetwork may include a broadcast network and/or a communication network,and the digital storage medium may include various storage media such asUSB, SD, CD, DVD, Blu-ray, HDD, and SSD. A transmitter (not shown) totransmit the signal output from the entropy encoder 15110 and/or astorage (not shown) to store the signal may be configured asinternal/external elements of the encoder 15000. Alternatively, thetransmitter may be included in the entropy encoder 15110.

The quantized transform coefficients output from the quantizer 15040 maybe used to generate a prediction signal. For example, inversequantization and inverse transform may be applied to the quantizedtransform coefficients through the inverse quantizer 15050 and theinverse transformer 15060 to reconstruct the residual signal (residualblock or residual samples). The adder 155 may add the reconstructedresidual signal to the prediction signal output from the inter-predictor15090 or the intra-predictor 15100. Thereby, a reconstructed signal(reconstructed picture, reconstructed block, reconstructed sample array)may be generated. When there is no residual signal for a processingtarget block as in the case where the skip mode is applied, thepredicted block may be used as the reconstructed block. The adder 155may be called a reconstructor or a reconstructed block generator. Thegenerated reconstructed signal may be used for intra-prediction of thenext processing target block in the current picture, or may be used forinter-prediction of the next picture through filtering as describedbelow.

The filter 15070 may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter15070 may generate a modified reconstructed picture by applying variousfiltering techniques to the reconstructed picture, and the modifiedreconstructed picture may be stored in the memory 15080, specifically,the DPB of the memory 15080. The various filtering techniques mayinclude, for example, deblocking filtering, sample adaptive offset,adaptive loop filtering, and bilateral filtering. As described below inthe description of the filtering techniques, the filter 15070 maygenerate various kinds of information about filtering and deliver thegenerated information to the entropy encoder 15110. The informationabout filtering may be encoded and output in the form of a bitstream bythe entropy encoder 15110.

The modified reconstructed picture transmitted to the memory 15080 maybe used as a reference picture by the inter-predictor 15090. Thus, wheninter-prediction is applied, the encoder may avoid prediction mismatchbetween the encoder 15000 and the decoder and improve encodingefficiency.

The DPB of the memory 15080 may store the modified reconstructed pictureso as to be used as a reference picture by the inter-predictor 15090.The memory 15080 may store the motion information about a block fromwhich the motion information in the current picture is derived (orencoded) and/or the motion information about the blocks in a picturethat has already been reconstructed. The stored motion information maybe delivered to the inter-predictor 15090 so as to be used as motioninformation about a spatial neighboring block or motion informationabout a temporal neighboring block. The memory 15080 may store thereconstructed samples of the reconstructed blocks in the current pictureand deliver the reconstructed samples to the intra-predictor 15100.

At least one of the prediction, transform, and quantization proceduresdescribed above may be skipped. For example, for a block to which thepulse coding mode (PCM) is applied, the prediction, transform, andquantization procedures may be skipped, and the value of the originalsample may be encoded and output in the form of a bitstream.

FIG. 16 illustrates an exemplary V-PCC decoding process according toembodiments.

The V-PCC decoding process or V-PCC decoder may follow the reverseprocess of the V-PCC encoding process (or encoder) of FIG. 4. Eachcomponent in FIG. 16 may correspond to software, hardware, a processor,and/or a combination thereof.

The demultiplexer 16000 demultiplexes the compressed bitstream to outputa compressed texture image, a compressed geometry image, a compressedoccupancy map, and compressed auxiliary patch information.

The video decompression or video decompressor 16001, 16002 decompresses(or decodes) each of the compressed texture image and the compressedgeometry image.

The occupancy map decompression or occupancy map decompressor 16003decompresses the compressed occupancy map.

The auxiliary patch info decompression or auxiliary patch infodecompressor 16004 decompresses auxiliary patch information.

The geometry reconstruction or geometry reconstructor 16005 restores(reconstructs) the geometry information based on the decompressedgeometry image, the decompressed occupancy map, and/or the decompressedauxiliary patch information. For example, the geometry changed in theencoding process may be reconstructed.

The smoothing or smoother 16006 may apply smoothing to the reconstructedgeometry. For example, smoothing filtering may be applied.

The texture reconstruction or texture reconstructor 16007 reconstructsthe texture from the decompressed texture image and/or the smoothedgeometry.

The color smoothing or color smoother 16008 smoothes color values fromthe reconstructed texture. For example, smoothing filtering may beapplied.

As a result, reconstructed point cloud data may be generated.

The figure illustrates a decoding process of the V-PCC forreconstructing a point cloud by decoding the compressed occupancy map,geometry image, texture image, and auxiliary path information. Eachprocess according to the embodiments is operated as follows.

Video Decompression (1600, 16002)

Video decompression is a reverse process of the video compressiondescribed above. In video decompression, a 2D video codec such as HEVCor VVC is used to decode a compressed bitstream containing the geometryimage, texture image, and occupancy map image generated in theabove-described process.

FIG. 17 illustrates an exemplary 2D video/image decoder according toembodiments.

The 2D video/image decoder may follow the reverse process of the 2Dvideo/image encoder of FIG. 15.

The 2D video/image decoder of FIG. 17 is an embodiment of the videodecompression or video decompressor of FIG. 16. FIG. 17 is a schematicblock diagram of a 2D video/image decoder 17000 by which decoding of avideo/image signal is performed. The 2D video/image decoder 17000 may beincluded in the point cloud video decoder of FIG. 1, or may beconfigured as an internal/external component. Each component in FIG. 17may correspond to software, hardware, a processor, and/or a combinationthereof.

Here, the input bitstream may include bitstreams for the geometry image,texture image (attribute(s) image), and occupancy map image describedabove. The reconstructed image (or the output image or the decodedimage) may represent a reconstructed image for the geometry image,texture image (attribute(s) image), and occupancy map image describedabove.

Referring to the figure, an inter-predictor 17070 and an intra-predictor17080 may be collectively referred to as a predictor. That is, thepredictor may include the inter-predictor 17070 and the intra-predictor17080. An inverse quantizer 17020 and an inverse transformer 17030 maybe collectively referred to as a residual processor. That is, theresidual processor may include the inverse quantizer 17020 and theinverse transformer 17030. The entropy decoder 17010, the inversequantizer 17020, the inverse transformer 17030, the adder 17040, thefilter 17050, the inter-predictor 17070, and the intra-predictor 17080described above may be configured by one hardware component (e.g., adecoder or a processor) according to an embodiment. In addition, thememory 170 may include a decoded picture buffer (DPB) or may beconfigured by a digital storage medium.

When a bitstream containing video/image information is input, thedecoder 17000 may reconstruct an image in a process corresponding to theprocess in which the video/image information is processed by the encoderof FIGS. 0.2-1. For example, the decoder 17000 may perform decodingusing a processing unit applied in the encoder. Thus, the processingunit of decoding may be, for example, a CU. The CU may be split from aCTU or an LCU along a quad-tree structure and/or a binary-treestructure. Then, the reconstructed video signal decoded and outputthrough the decoder 17000 may be played through a player.

The decoder 17000 may receive a signal output from the encoder in theform of a bitstream, and the received signal may be decoded through theentropy decoder 17010. For example, the entropy decoder 17010 may parsethe bitstream to derive information (e.g., video/image information)necessary for image reconstruction (or picture reconstruction). Forexample, the entropy decoder 17010 may decode the information in thebitstream based on a coding technique such as exponential Golomb coding,CAVLC, or CABAC, output values of syntax elements required for imagereconstruction, and quantized values of transform coefficients for theresidual. More specifically, in the CABAC entropy decoding, a bincorresponding to each syntax element in the bitstream may be received,and a context model may be determined based on decoding target syntaxelement information and decoding information about neighboring anddecoding target blocks or information about a symbol/bin decoded in aprevious step. Then, the probability of occurrence of a bin may bepredicted according to the determined context model, and arithmeticdecoding of the bin may be performed to generate a symbol correspondingto the value of each syntax element. According to the CABAC entropydecoding, after a context model is determined, the context model may beupdated based on the information about the symbol/bin decoded for thecontext model of the next symbol/bin. Information about the predictionin the information decoded by the entropy decoder 17010 may be providedto the predictors (the inter-predictor 17070 and the intra-predictor17080), and the residual values on which entropy decoding has beenperformed by the entropy decoder 17010, that is, the quantized transformcoefficients and related parameter information, may be input to theinverse quantizer 17020. In addition, information about filtering of theinformation decoded by the entropy decoder 17010 may be provided to thefilter 17050. A receiver (not shown) configured to receive a signaloutput from the encoder may be further configured as aninternal/external element of the decoder 17000. Alternatively, thereceiver may be a component of the entropy decoder 17010.

The inverse quantizer 17020 may output transform coefficients byinversely quantizing the quantized transform coefficients. The inversequantizer 17020 may rearrange the quantized transform coefficients inthe form of a two-dimensional block. In this case, the rearrangement maybe performed based on the coefficient scan order implemented by theencoder. The inverse quantizer 17020 may perform inverse quantization onthe quantized transform coefficients using a quantization parameter(e.g., quantization step size information), and acquire transformcoefficients.

The inverse transformer 17030 acquires a residual signal (residual blockand residual sample array) by inversely transforming the transformcoefficients.

The predictor may perform prediction on the current block and generate apredicted block including prediction samples for the current block. Thepredictor may determine whether intra-prediction or inter-prediction isto be applied to the current block based on the information about theprediction output from the entropy decoder 17010, and may determine aspecific intra-/inter-prediction mode.

The intra-predictor 265 may predict the current block with reference tothe samples in the current picture. The samples may be positioned in theneighbor of or away from the current block depending on the predictionmode. In intra-prediction, the prediction modes may include a pluralityof non-directional modes and a plurality of directional modes. Theintra-predictor 17080 may determine a prediction mode to be applied tothe current block, using the prediction mode applied to the neighboringblock.

The inter-predictor 17070 may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on the reference picture. In this case, in order to reducethe amount of motion information transmitted in the inter-predictionmode, the motion information may be predicted on a per block, subblock,or sample basis based on the correlation in motion information betweenthe neighboring blocks and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include information about an inter-predictiondirection (L0 prediction, L1 prediction, Bi prediction, etc.). In thecase of inter-prediction, the neighboring blocks may include a spatialneighboring block, which is present in the current picture, and atemporal neighboring block, which is present in the reference picture.For example, the inter-predictor 17070 may configure a motioninformation candidate list based on neighboring blocks and derive amotion vector of the current block and/or a reference picture indexbased on the received candidate selection information. Inter-predictionmay be performed based on various prediction modes. The informationabout the prediction may include information indicating aninter-prediction mode for the current block.

The adder 17040 may add the acquired residual signal to the predictionsignal (predicted block or prediction sample array) output from theinter-predictor 17070 or the intra-predictor 17080, thereby generating areconstructed signal (a reconstructed picture, a reconstructed block, ora reconstructed sample array). When there is no residual signal for aprocessing target block as in the case where the skip mode is applied,the predicted block may be used as the reconstructed block.

The adder 17040 may be called a reconstructor or a reconstructed blockgenerator. The generated reconstructed signal may be used forintra-prediction of the next processing target block in the currentpicture, or may be used for inter-prediction of the next picture throughfiltering as described below.

The filter 17050 may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter17050 may generate a modified reconstructed picture by applying variousfiltering techniques to the reconstructed picture, and may transmit themodified reconstructed picture to the memory 250, specifically, the DPBof the memory 17060. The various filtering techniques may include, forexample, deblocking filtering, sample adaptive offset, adaptive loopfiltering, and bilateral filtering.

The reconstructed picture stored in the DPB of the memory 17060 may beused as a reference picture in the inter-predictor 17070. The memory17060 may store the motion information about a block from which themotion information is derived (or decoded) in the current picture and/orthe motion information about the blocks in a picture that has alreadybeen reconstructed. The stored motion information may be delivered tothe inter-predictor 17070 so as to be used as the motion informationabout a spatial neighboring block or the motion information about atemporal neighboring block. The memory 17060 may store the reconstructedsamples of the reconstructed blocks in the current picture, and deliverthe reconstructed samples to the intra-predictor 17080.

In the present disclosure, the embodiments described regarding thefilter 160, the inter-predictor 180, and the intra-predictor 185 of theencoder 100 may be applied to the filter 17050, the inter-predictor17070 and the intra-predictor 17080 of the decoder 17000, respectively,in the same or corresponding manner.

At least one of the prediction, transform, and quantization proceduresdescribed above may be skipped. For example, for a block to which thepulse coding mode (PCM) is applied, the prediction, transform, andquantization procedures may be skipped, and the value of a decodedsample may be used as a sample of the reconstructed image.

Occupancy Map Decompression (16003)

This is a reverse process of the occupancy map compression describedabove. Occupancy map decompression is a process for reconstructing theoccupancy map by decompressing the occupancy map bitstream.

Auxiliary Patch Info Decompression (16004)

The auxiliary patch information may be reconstructed by performing thereverse process of the aforementioned auxiliary patch info compressionand decoding the compressed auxiliary patch info bitstream.

Geometry Reconstruction (16005)

This is a reverse process of the geometry image generation describedabove. Initially, a patch is extracted from the geometry image using thereconstructed occupancy map, the 2D position/size information about thepatch included in the auxiliary patch info, and the information aboutmapping between a block and the patch. Then, a point cloud isreconstructed in a 3D space based on the geometry image of the extractedpatch and the 3D position information about the patch included in theauxiliary patch info. When the geometry value corresponding to a point(u, v) within the patch is g(u, v), and the coordinates of the positionof the patch on the normal, tangent and bitangent axes of the 3D spaceare (δ0, s0, r0), □δ(u, v), s(u, v), and r(u, v), which are the normal,tangent, and bitangent coordinates in the 3D space of a position mappedto point (u, v) may be expressed as follows:

δ(u,v)=δ0+g(u,v);

s(u,v)=s0+u;

r(u,v)=r0+v.

Smoothing (16006)

Smoothing, which is the same as the smoothing in the encoding processdescribed above, is a process for eliminating discontinuity that mayoccur on the patch boundary due to deterioration of the image qualityoccurring during the compression process.

Texture Reconstruction (16007)

Texture reconstruction is a process of reconstructing a color pointcloud by assigning color values to each point constituting a smoothedpoint cloud. It may be performed by assigning color values correspondingto a texture image pixel at the same position as in the geometry imagein the 2D space to points of a point of a point cloud corresponding tothe same position in the 3D space, based on the mapping informationabout the geometry image and the point cloud in the geometryreconstruction process described above.

Color Smoothing (16008)

Color smoothing is similar to the process of geometry smoothingdescribed above. Color smoothing is a process for eliminatingdiscontinuity that may occur on the patch boundary due to deteriorationof the image quality occurring during the compression process. Colorsmoothing may be performed through the following operations:

1) Calculate neighboring points of each point constituting thereconstructed point cloud using the K-D tree or the like. Theneighboring point information calculated in the geometry smoothingprocess described in section 2.5 may be used.

2) Determine whether each of the points is positioned on the patchboundary. These operations may be performed based on the boundaryinformation calculated in the geometry smoothing process describedabove.

3) Check the distribution of color values for the neighboring points ofthe points present on the boundary and determine whether smoothing is tobe performed. For example, when the entropy of luminance values is lessthan or equal to a threshold local entry (there are many similarluminance values), it may be determined that the corresponding portionis not an edge portion, and smoothing may be performed. As a method ofsmoothing, the color value of the point may be replaced with the averageof the color values of the neighboring points.

FIG. 18 is a flowchart illustrating operation of a transmission deviceaccording to embodiments of the present disclosure.

The transmission device according to the embodiments may correspond tothe transmission device of FIG. 1, the encoding process of FIG. 4, andthe 2D video/image encoder of FIG. 15, or perform some/all of theoperations thereof. Each component of the transmission device maycorrespond to software, hardware, a processor and/or a combinationthereof.

An operation process of the transmission terminal for compression andtransmission of point cloud data using V-PCC may be performed asillustrated in the figure.

The point cloud data transmission device according to the embodimentsmay be referred to as a transmission device.

Regarding a patch generator 18000, a patch for 2D image mapping of apoint cloud is generated. Auxiliary patch information is generated as aresult of the patch generation. The generated information may be used inthe processes of geometry image generation, texture image generation,and geometry reconstruction for smoothing.

Regarding a patch packer 18001, a patch packing process of mapping thegenerated patches into the 2D image is performed. As a result of patchpacking, an occupancy map may be generated. The occupancy map may beused in the processes of geometry image generation, texture imagegeneration, and geometry reconstruction for smoothing.

A geometry image generator 18002 generates a geometry image based on theauxiliary patch information and the occupancy map. The generatedgeometry image is encoded into one bitstream through video encoding.

An encoding preprocessor 18003 may include an image padding procedure.The geometry image regenerated by decoding the generated geometry imageor the encoded geometry bitstream may be used for 3D geometryreconstruction and then be subjected to a smoothing process.

A texture image generator 18004 may generate a texture image based onthe (smoothed) 3D geometry, the point cloud, the auxiliary patchinformation, and the occupancy map. The generated texture image may beencoded into one video bitstream.

A metadata encoder 18005 may encode the auxiliary patch information intoone metadata bitstream.

A video encoder 18006 may encode the occupancy map into one videobitstream.

A multiplexer 18007 may multiplex the video bitstreams of the generatedgeometry image, texture image, and occupancy map and the metadatabitstream of the auxiliary patch information into one bitstream.

A transmitter 18008 may transmit the bitstream to the receptionterminal. Alternatively, the video bitstreams of the generated geometryimage, texture image, and the occupancy map and the metadata bitstreamof the auxiliary patch information may be processed into a file of oneor more track data or encapsulated into segments and may be transmittedto the reception terminal through the transmitter.

FIG. 19 is a flowchart illustrating operation of a reception deviceaccording to embodiments.

The reception device according to the embodiments may correspond to thereception device of FIG. 1, the decoding process of FIG. 16, and the 2Dvideo/image encoder of FIG. 17, or perform some/all of the operationsthereof. Each component of the reception device may correspond tosoftware, hardware, a processor and/or a combination thereof.

The operation of the reception terminal for receiving and reconstructingpoint cloud data using V-PCC may be performed as illustrated in thefigure. The operation of the V-PCC reception terminal may follow thereverse process of the operation of the V-PCC transmission terminal ofFIG. 18.

The point cloud data reception device according to the embodiments maybe referred to as a reception device.

The bitstream of the received point cloud is demultiplexed into thevideo bitstreams of the compressed geometry image, texture image,occupancy map and the metadata bitstream of the auxiliary patchinformation by a demultiplexer 19000 after file/segment decapsulation. Avideo decoder 19001 and a metadata decoder 19002 decode thedemultiplexed video bitstreams and metadata bitstream. 3D geometry isreconstructed by a geometry reconstructor 19003 based on the decodedgeometry image, occupancy map, and auxiliary patch information, and isthen subjected to a smoothing process performed by a smoother 19004. Acolor point cloud image/picture may be reconstructed by a texturereconstructor 19005 by assigning color values to the smoothed 3Dgeometry based on the texture image. Thereafter, a color smoothingprocess may be additionally performed to improve theobjective/subjective visual quality, and a modified point cloudimage/picture derived through the color smoothing process is shown tothe user through the rendering process (through, for example, the pointcloud renderer). In some cases, the color smoothing process may beskipped.

FIG. 20 illustrates an exemplary architecture for V-PCC based storageand streaming of point cloud data according to embodiments.

A part/the entirety of the system of FIG. 20 may include some or all ofthe transmission device and reception device of FIG. 1, the encodingprocess of FIG. 4, the 2D video/image encoder of FIG. 15, the decodingprocess of FIG. 16, the transmission device of FIG. 18, and/or thereception device of FIG. 19. Each component in the figure may correspondto software, hardware, a processor and/or a combination thereof.

FIGS. 20 to 22 are diagrams illustrating a structure in which a systemis additionally connected to the transmission device and the receptiondevice according to embodiments. The transmission device and thereception device the system according to embodiments may be referred toas a transmission/reception apparatus according to the embodiments.

In the apparatus according to the embodiments illustrated in FIGS. 20 to22, the transmitting device corresponding to FIG. 18 or the like maygenerate a container suitable for a data format for transmission of abitstream containing encoded point cloud data.

The V-PCC system according to the embodiments may create a containerincluding point cloud data, and may further add additional datanecessary for efficient transmission/reception to the container.

The reception device according to the embodiments may receive and parsethe container based on the system shown in FIGS. 20 to 22. The receptiondevice corresponding to FIG. 19 or the like may decode and restore pointcloud data from the parsed bitstream.

The figure shows the overall architecture for storing or streaming pointcloud data compressed based on video-based point cloud compression(V-PCC). The process of storing and streaming the point cloud data mayinclude an acquisition process, an encoding process, a transmissionprocess, a decoding process, a rendering process, and/or a feedbackprocess.

The embodiments propose a method of effectively providing point cloudmedia/content/data.

In order to effectively provide point cloud media/content/data, a pointcloud acquirer 20000 may acquire a point cloud video. For example, oneor more cameras may acquire point cloud data through capture,composition or generation of a point cloud. Through this acquisitionprocess, a point cloud video including a 3D position (which may berepresented by x, y, and z position values, etc.) (hereinafter referredto as geometry) of each point and attributes (color, reflectance,transparency, etc.) of each point may be acquired. For example, aPolygon File format (PLY) (or Stanford Triangle format) file or the likecontaining the point cloud video may be generated. For point cloud datahaving multiple frames, one or more files may be acquired. In thisprocess, point cloud related metadata (e.g., metadata related tocapture, etc.) may be generated.

Post-processing for improving the quality of the content may be neededfor the captured point cloud video. In the video capture process, themaximum/minimum depth may be adjusted within the range provided by thecamera equipment. Even after the adjustment, point data of an unwantedarea may still be present. Accordingly, post-processing of removing theunwanted area (e.g., the background) or recognizing a connected spaceand filling the spatial holes may be performed. In addition, pointclouds extracted from the cameras sharing a spatial coordinate systemmay be integrated into one piece of content through the process oftransforming each point into a global coordinate system based on thecoordinates of the location of each camera acquired through acalibration process. Thereby, a point cloud video with a high density ofpoints may be acquired.

A point cloud pre-processor 20001 may generate one or morepictures/frames of the point cloud video. Here, a picture/frame maygenerally represent a unit representing one image in a specific timeinterval. When points constituting the point cloud video is divided intoone or more patches (sets of points that constitute the point cloudvideo, wherein the points belonging to the same patch are adjacent toeach other in the 3D space and are mapped in the same direction amongthe planar faces of a 6-face bounding box when mapped to a 2D image) andmapped to a 2D plane, an occupancy map picture/frame of a binary map,which indicates presence or absence of data at the correspondingposition in the 2D plane with a value of 0 or 1 may be generated. Inaddition, a geometry picture/frame, which is in the form of a depth mapthat represents the information about the position (geometry) of eachpoint constituting the point cloud video on a patch-by-patch basis, maybe generated. A texture picture/frame, which represents the colorinformation about each point constituting the point cloud video on apatch-by-patch basis, may be generated. In this process, metadata neededto reconstruct the point cloud from the individual patches may begenerated. The metadata may include information about the patches, suchas the position and size of each patch in the 2D/3D space. Thesepictures/frames may be generated continuously in temporal order toconstruct a video stream or metadata stream.

A point cloud video encoder 20002 may encode one or more video streamsrelated to a point cloud video. One video may include multiple frames,and one frame may correspond to a still image/picture. In the presentdisclosure, the point cloud video may include a point cloudimage/frame/picture, and the term “point cloud video” may be usedinterchangeably with the point cloud video/frame/picture. The pointcloud video encoder may perform a video-based point cloud compression(V-PCC) procedure. The point cloud video encoder may perform a series ofprocedures such as prediction, transform, quantization, and entropycoding for compression and coding efficiency. The encoded data (encodedvideo/image information) may be output in the form of a bitstream. Basedon the V-PCC procedure, the point cloud video encoder may encode pointcloud video by dividing the same into a geometry video, an attributevideo, an occupancy map video, and metadata, for example, informationabout patches, as described below. The geometry video may include ageometry image, the attribute video may include an attribute image, andthe occupancy map video may include an occupancy map image. The patchdata, which is auxiliary information, may include patch relatedinformation. The attribute video/image may include a texturevideo/image.

A point cloud image encoder 20003 may encode one or more images relatedto a point cloud video. The point cloud image encoder may perform avideo-based point cloud compression (V-PCC) procedure. The point cloudimage encoder may perform a series of procedures such as prediction,transform, quantization, and entropy coding for compression and codingefficiency. The encoded image may be output in the form of a bitstream.Based on the V-PCC procedure, the point cloud image encoder may encodethe point cloud image by dividing the same into a geometry image, anattribute image, an occupancy map image, and metadata, for example,information about patches, as described below.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may generate a PCC bitstream (G-PCC and/orV-PCC bitstream) according to the embodiments.

According to embodiments, the video encoder 20002, the image encoder20002, the video decoding 20006, and the image decoding may be performedby one encoder/decoder as described above, and may be performed alongseparate paths as shown in the figure.

In file/segment encapsulation 20004, the encoded point cloud data and/orpoint cloud-related metadata may be encapsulated into a file or asegment for streaming. Here, the point cloud-related metadata may bereceived from the metadata processor or the like. The metadata processormay be included in the point cloud video/image encoder or may beconfigured as a separate component/module. The encapsulation processormay encapsulate the corresponding video/image/metadata in a file formatsuch as ISOBMFF or in the form of a DASH segment or the like. Accordingto an embodiment, the encapsulation processor may include the pointcloud metadata in the file format. The point cloud-related metadata maybe included, for example, in boxes at various levels on the ISOBMFF fileformat or as data in a separate track within the file. According to anembodiment, the encapsulation processor may encapsulate the pointcloud-related metadata into a file.

The encapsulation or encapsulator according to the embodiments maydivide the G-PCC/V-PCC bitstream into one or multiple tracks and storethe same in a file, and may also encapsulate signaling information forthis operation. In addition, the atlas stream included on theG-PCC/V-PCC bitstream may be stored as a track in the file, and relatedsignaling information may be stored. Furthermore, an SEI message presentin the G-PCC/V-PCC bitstream may be stored in a track in the file andrelated signaling information may be stored.

A transmission processor may perform processing of the encapsulatedpoint cloud data for transmission according to the file format. Thetransmission processor may be included in the transmitter or may beconfigured as a separate component/module. The transmission processormay process the point cloud data according to a transmission protocol.The processing for transmission may include processing for delivery overa broadcast network and processing for delivery through a broadband.According to an embodiment, the transmission processor may receive pointcloud-related metadata from the metadata processor as well as the pointcloud data, and perform processing of the point cloud video data fortransmission.

The transmitter may transmit a point cloud bitstream or a file/segmentincluding the bitstream to the receiver of the reception device over adigital storage medium or a network. For transmission, processingaccording to any transmission protocol may be performed. The dataprocessed for transmission may be delivered over a broadcast networkand/or through a broadband. The data may be delivered to the receptionside in an on-demand manner. The digital storage medium may includevarious storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.The transmitter may include an element for generating a media file in apredetermined file format, and may include an element for transmissionover a broadcast/communication network. The receiver may extract thebitstream and transmit the extracted bitstream to the decoder.

The receiver may receive point cloud data transmitted by the point clouddata transmission device according to the present disclosure. Dependingon the transmission channel, the receiver may receive the point clouddata over a broadcast network or through a broadband. Alternatively, thepoint cloud data may be received through the digital storage medium. Thereceiver may include a process of decoding the received data andrendering the data according to the viewport of the user.

The reception processor may perform processing on the received pointcloud video data according to the transmission protocol. The receptionprocessor may be included in the receiver or may be configured as aseparate component/module. The reception processor may reversely performthe process of the transmission processor above described so as tocorrespond to the processing for transmission performed at thetransmission side. The reception processor may deliver the acquiredpoint cloud video to a decapsulation processor, and the acquired pointcloud-related metadata to a metadata parser.

A decapsulation processor (file/segment decapsulation) 20005 maydecapsulate the point cloud data received in the form of a file from thereception processor. The decapsulation processor may decapsulate filesaccording to ISOBMFF or the like, and may acquire a point cloudbitstream or point cloud-related metadata (or a separate metadatabitstream). The acquired point cloud bitstream may be delivered to thepoint cloud decoder, and the acquired point cloud video-related metadata(metadata bitstream) may be delivered to the metadata processor. Thepoint cloud bitstream may include the metadata (metadata bitstream). Themetadata processor may be included in the point cloud decoder or may beconfigured as a separate component/module. The point cloud video-relatedmetadata acquired by the decapsulation processor may take the form of abox or track in the file format. The decapsulation processor may receivemetadata necessary for decapsulation from the metadata processor, whennecessary. The point cloud-related metadata may be delivered to thepoint cloud decoder and used in a point cloud decoding procedure, or maybe transferred to the renderer and used in a point cloud renderingprocedure.

The point cloud video decoder 20006 may receive the bitstream and decodethe video/image by performing an operation corresponding to theoperation of the point cloud video encoder. In this case, the pointcloud video decoder may decode the point cloud video by dividing thesame into a geometry video, an attribute video, an occupancy map video,and auxiliary patch information as described below. The geometry videomay include a geometry image, the attribute video may include anattribute image, and the occupancy map video may include an occupancymap image. The auxiliary information may include auxiliary patchinformation. The attribute video/image may include a texturevideo/image.

The 3D geometry may be reconstructed based on the decoded geometryimage, the occupancy map, and auxiliary patch information, and then maybe subjected to a smoothing process. The color point cloud image/picturemay be reconstructed by assigning a color value to the smoothed 3Dgeometry based on the texture image. The renderer may render thereconstructed geometry and the color point cloud image/picture. Therendered video/image may be displayed through the display. All or partof the rendered result may be shown to the user through a VR/AR displayor a typical display.

A sensor/tracker (sensing/tracking) 20007 acquires orientationinformation and/or user viewport information from the user or thereception side and delivers the orientation information and/or the userviewport information to the receiver and/or the transmitter. Theorientation information may represent information about the position,angle, movement, etc. of the user's head, or represent information aboutthe position, angle, movement, etc. of a device through which the useris viewing a video/image. Based on this information, information aboutthe area currently viewed by the user in a 3D space, that is, viewportinformation may be calculated.

The viewport information may be information about an area in a 3D spacecurrently viewed by the user through a device or an HMD. A device suchas a display may extract a viewport area based on the orientationinformation, a vertical or horizontal FOV supported by the device, andthe like. The orientation or viewport information may be extracted orcalculated at the reception side. The orientation or viewportinformation analyzed at the reception side may be transmitted to thetransmission side on a feedback channel.

Based on the orientation information acquired by the sensor/trackerand/or the viewport information indicating the area currently viewed bythe user, the receiver may efficiently extract or decode only media dataof a specific area, i.e., the area indicated by the orientationinformation and/or the viewport information from the file. In addition,based on the orientation information and/or viewport informationacquired by the sensor/tracker, the transmitter may efficiently encodeonly the media data of the specific area, that is, the area indicated bythe orientation information and/or the viewport information, or generateand transmit a file therefor.

The renderer may render the decoded point cloud data in a 3D space. Therendered video/image may be displayed through the display. The user mayview all or part of the rendered result through a VR/AR display or atypical display.

The feedback process may include transferring various kinds of feedbackinformation that may be acquired in the rendering/displaying process tothe transmitting side or the decoder of the receiving side. Through thefeedback process, interactivity may be provided in consumption of pointcloud data. According to an embodiment, head orientation information,viewport information indicating an area currently viewed by a user, andthe like may be delivered to the transmitting side in the feedbackprocess. According to an embodiment, the user may interact with what isimplemented in the VR/AR/MR/autonomous driving environment. In thiscase, information related to the interaction may be delivered to thetransmitting side or a service provider in the feedback process.According to an embodiment, the feedback process may be skipped.

According to an embodiment, the above-described feedback information maynot only be transmitted to the transmitting side, but also be consumedat the receiving side. That is, the decapsulation processing, decoding,and rendering processes at the receiving side may be performed based onthe above-described feedback information. For example, the point clouddata about the area currently viewed by the user may be preferentiallydecapsulated, decoded, and rendered based on the orientation informationand/or the viewport information.

FIG. 21 is an exemplary block diagram of an device for storing andtransmitting point cloud data according to embodiments.

FIG. 21 shows a point cloud system according to embodiments. A part/theentirety of the system may include some or all of the transmissiondevice and reception device of FIG. 1, the encoding process of FIG. 4,the 2D video/image encoder of FIG. 15, the decoding process of FIG. 16,the transmission device of FIG. 18, and/or the reception device of FIG.19. In addition, it may be included or corresponded to a part/theentirety of the system of FIG. 20.

A point cloud data transmission device according to embodiments may beconfigured as shown in the figure. Each element of the transmissiondevice may be a module/unit/component/hardware/software/a processor.

The geometry, attribute, auxiliary data, and mesh data of the pointcloud may each be configured as a separate stream or stored in differenttracks in a file. Furthermore, they may be included in a separatesegment.

A point cloud acquirer (point cloud acquisition) 21000 acquires a pointcloud. For example, one or more cameras may acquire point cloud datathrough capture, composition or generation of a point cloud. Throughthis acquisition process, point cloud data including a 3D position(which may be represented by x, y, and z position values, etc.)(hereinafter referred to as geometry) of each point and attributes(color, reflectance, transparency, etc.) of each point may be acquired.For example, a Polygon File format (PLY) (or Stanford Triangle format)file or the like including the point cloud data may be generated. Forpoint cloud data having multiple frames, one or more files may beacquired. In this process, point cloud related metadata (e.g., metadatarelated to capture, etc.) may be generated.

A patch generator (or patch generation) 21002 generates patches from thepoint cloud data. The patch generator generates point cloud data orpoint cloud video as one or more pictures/frames. A picture/frame maygenerally represent a unit representing one image in a specific timeinterval. When points constituting the point cloud video is divided intoone or more patches (sets of points that constitute the point cloudvideo, wherein the points belonging to the same patch are adjacent toeach other in the 3D space and are mapped in the same direction amongthe planar faces of a 6-face bounding box when mapped to a 2D image) andmapped to a 2D plane, an occupancy map picture/frame in a binary map,which indicates presence or absence of data at the correspondingposition in the 2D plane with 0 or 1 may be generated. In addition, ageometry picture/frame, which is in the form of a depth map thatrepresents the information about the position (geometry) of each pointconstituting the point cloud video on a patch-by-patch basis, may begenerated. A texture picture/frame, which represents the colorinformation about each point constituting the point cloud video on apatch-by-patch basis, may be generated. In this process, metadata neededto reconstruct the point cloud from the individual patches may begenerated. The metadata may include information about the patches, suchas the position and size of each patch in the 2D/3D space. Thesepictures/frames may be generated continuously in temporal order toconstruct a video stream or metadata stream.

In addition, the patches may be used for 2D image mapping. For example,the point cloud data may be projected onto each face of a cube. Afterpatch generation, a geometry image, one or more attribute images, anoccupancy map, auxiliary data, and/or mesh data may be generated basedon the generated patches.

Geometry image generation, attribute image generation, occupancy mapgeneration, auxiliary data generation, and/or mesh data generation areperformed by a pre-processor or a controller.

In geometry image generation 21002, a geometry image is generated basedon the result of the patch generation. Geometry represents a point in a3D space. The geometry image is generated using the occupancy map, whichincludes information related to 2D image packing of the patches,auxiliary data (patch data), and/or mesh data based on the patches. Thegeometry image is related to information such as a depth (e.g., near,far) of the patch generated after the patch generation.

In attribute image generation 21003, an attribute image is generated.For example, an attribute may represent a texture. The texture may be acolor value that matches each point. According to embodiments, images ofa plurality of attributes (such as color and reflectance) (N attributes)including a texture may be generated. The plurality of attributes mayinclude material information and reflectance. According to anembodiment, the attributes may additionally include informationindicating a color, which may vary depending on viewing angle and lighteven for the same texture.

In occupancy map generation 21004, an occupancy map is generated fromthe patches. The occupancy map includes information indicating presenceor absence of data in the pixel, such as the corresponding geometry orattribute image.

In auxiliary data generation 21005, auxiliary data including informationabout the patches is generated. That is, the auxiliary data representsmetadata about a patch of a point cloud object. For example, it mayrepresent information such as normal vectors for the patches.Specifically, the auxiliary data may include information needed toreconstruct the point cloud from the patches (e.g., information aboutthe positions, sizes, and the like of the patches in 2D/3D space, andprojection (normal) plane identification information, patch mappinginformation, etc.)

In mesh data generation 21006, mesh data is generated from the patches.Mesh represents connection between neighboring points. For example, itmay represent data of a triangular shape. For example, the mesh datarefers to connectivity between the points.

A point cloud pre-processor or controller generates metadata related topatch generation, geometry image generation, attribute image generation,occupancy map generation, auxiliary data generation, and mesh datageneration.

The point cloud transmission device performs video encoding and/or imageencoding in response to the result generated by the pre-processor. Thepoint cloud transmission device may generate point cloud image data aswell as point cloud video data. According to embodiments, the pointcloud data may have only video data, only image data, and/or both videodata and image data.

A video encoder 21007 performs geometry video compression, attributevideo compression, occupancy map compression, auxiliary datacompression, and/or mesh data compression. The video encoder generatesvideo stream(s) containing encoded video data.

Specifically, in the geometry video compression, point cloud geometryvideo data is encoded. In the attribute video compression, attributevideo data of the point cloud is encoded. In the auxiliary datacompression, auxiliary data associated with the point cloud video datais encoded. In the mesh data compression, mesh data of the point cloudvideo data is encoded. The respective operations of the point cloudvideo encoder may be performed in parallel.

An image encoder 21008 performs geometry image compression, attributeimage compression, occupancy map compression, auxiliary datacompression, and/or mesh data compression. The image encoder generatesimage(s) containing encoded image data.

Specifically, in the geometry image compression, the point cloudgeometry image data is encoded. In the attribute image compression, theattribute image data of the point cloud is encoded. In the auxiliarydata compression, the auxiliary data associated with the point cloudimage data is encoded. In the mesh data compression, the mesh dataassociated with the point cloud image data is encoded. The respectiveoperations of the point cloud image encoder may be performed inparallel.

The video encoder and/or the image encoder may receive metadata from thepre-processor. The video encoder and/or the image encoder may performeach encoding process based on the metadata.

A file/segment encapsulator (file/segment encapsulation) 21009encapsulates the video stream(s) and/or image(s) in the form of a fileand/or segment. The file/segment encapsulator performs video trackencapsulation, metadata track encapsulation, and/or image encapsulation.

In the video track encapsulation, one or more video streams may beencapsulated into one or more tracks.

In the metadata track encapsulation, metadata related to a video streamand/or an image may be encapsulated in one or more tracks. The metadataincludes data related to the content of the point cloud data. Forexample, it may include initial viewing orientation metadata. Accordingto embodiments, the metadata may be encapsulated into a metadata track,or may be encapsulated together in a video track or an image track.

In the image encapsulation, one or more images may be encapsulated intoone or more tracks or items.

For example, according to embodiments, when four video streams and twoimages are input to the encapsulator, the four video streams and twoimages may be encapsulated in one file.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may generate a G-PCC/V-PCC bitstreamaccording to the embodiments.

The file/segment encapsulator may receive metadata from thepre-processor. The file/segment encapsulator may perform encapsulationbased on the metadata.

A file and/or a segment generated by the file/segment encapsulation aretransmitted by the point cloud transmission device or the transmitter.For example, the segment(s) may be delivered based on a DASH-basedprotocol.

The encapsulation or encapsulator according to the embodiments maydivide the V-PCC bitstream into one or multiple tracks and store thesame in a file, and may also encapsulate signaling information for thisoperation. In addition, the atlas stream included on the V-PCC bitstreammay be stored as a track in the file, and related signaling informationmay be stored. Furthermore, an SEI message present in the V-PCCbitstream may be stored in a track in the file and related signalinginformation may be stored.

The transmitter may transmit a point cloud bitstream or a file/segmentincluding the bitstream to the receiver of the reception device over adigital storage medium or a network. Processing according to anytransmission protocol may be performed for transmission. The data thathas been processed for transmission may be delivered over a broadcastnetwork and/or through a broadband. The data may be delivered to thereceiving side in an on-demand manner. The digital storage medium mayinclude various storage media such as USB, SD, CD, DVD, Blu-ray, HDD,and SSD. The deliverer may include an element for generating a mediafile in a predetermined file format, and may include an element fortransmission over a broadcast/communication network. The delivererreceives orientation information and/or viewport information from thereceiver. The deliverer may deliver the acquired orientation informationand/or viewport information (or information selected by the user) to thepre-processor, the video encoder, the image encoder, the file/segmentencapsulator, and/or the point cloud encoder. Based on the orientationinformation and/or the viewport information, the point cloud encoder mayencode all point cloud data or the point cloud data indicated by theorientation information and/or the viewport information. Based on theorientation information and/or the viewport information, thefile/segment encapsulator may encapsulate all point cloud data or thepoint cloud data indicated by the orientation information and/or theviewport information. Based on the orientation information and/or theviewport information, the deliverer may deliver all point cloud data orthe point cloud data indicated by the orientation information and/or theviewport information.

For example, the pre-processor may perform the above-described operationon all the point cloud data or on the point cloud data indicated by theorientation information and/or the viewport information. The videoencoder and/or the image encoder may perform the above-describedoperation on all the point cloud data or on the point cloud dataindicated by the orientation information and/or the viewportinformation. The file/segment encapsulator may perform theabove-described operation on all the point cloud data or on the pointcloud data indicated by the orientation information and/or the viewportinformation. The transmitter may perform the above-described operationon all the point cloud data or on the point cloud data indicated by theorientation information and/or the viewport information.

FIG. 22 is an exemplary block diagram of a point cloud data receptiondevice according to embodiments.

FIG. 22 shows a point cloud system according to embodiments. A part/theentirety of the system may include some or all of the transmissiondevice and reception device of FIG. 1, the encoding process of FIG. 4,the 2D video/image encoder of FIG. 15, the decoding process of FIG. 16,the transmission device of FIG. 18, and/or the reception device of FIG.19. In addition, it may be included or corresponded to a part/theentirety of the system of FIGS. 20 and 21.

Each component of the reception device may be amodule/unit/component/hardware/software/processor. A delivery client mayreceive point cloud data, a point cloud bitstream, or a file/segmentincluding the bitstream transmitted by the point cloud data transmissiondevice according to the embodiments. The receiver may receive the pointcloud data over a broadcast network or through a broadband depending onthe channel used for the transmission. Alternatively, the point cloudvideo data may be received through a digital storage medium. Thereceiver may include a process of decoding the received data andrendering the received data according to the user viewport. Thereception processor may perform processing on the received point clouddata according to a transmission protocol. A reception processor may beincluded in the receiver or configured as a separate component/module.The reception processor may reversely perform the process of thetransmission processor described above so as to correspond to theprocessing for transmission performed at the transmitting side. Thereception processor may deliver the acquired point cloud data to thedecapsulation processor and the acquired point cloud related metadata tothe metadata parser.

The sensor/tracker (sensing/tracking) acquires orientation informationand/or viewport information. The sensor/tracker may deliver the acquiredorientation information and/or viewport information to the deliveryclient, the file/segment decapsulator, and the point cloud decoder.

The delivery client may receive all point cloud data or the point clouddata indicated by the orientation information and/or the viewportinformation based on the orientation information and/or the viewportinformation. The file/segment decapsulator may decapsulate all pointcloud data or the point cloud data indicated by the orientationinformation and/or the viewport information based on the orientationinformation and/or the viewport information. The point cloud decoder(the video decoder and/or the image decoder) may decode all point clouddata or the point cloud data indicated by the orientation informationand/or the viewport information based on the orientation informationand/or the viewport information. The point cloud processor may processall point cloud data or the point cloud data indicated by theorientation information and/or the viewport information based on theorientation information and/or the viewport information.

A file/segment decapsulator (file/segment decapsulation) 22000 performsvideo track decapsulation, metadata track decapsulation, and/or imagedecapsulation. The decapsulation processor (file/segment decapsulation)may decapsulate the point cloud data in the form of a file received fromthe reception processor. The decapsulation processor (file/segmentdecapsulation) may decapsulate files or segments according to ISOBMFF,etc., to acquire a point cloud bitstream or point cloud-related metadata(or a separate metadata bitstream). The acquired point cloud bitstreammay be delivered to the point cloud decoder, and the acquired pointcloud-related metadata (or metadata bitstream) may be delivered to themetadata processor. The point cloud bitstream may include the metadata(metadata bitstream). The metadata processor may be included in thepoint cloud video decoder or may be configured as a separatecomponent/module. The point cloud-related metadata acquired by thedecapsulation processor may take the form of a box or track in a fileformat. The decapsulation processor may receive metadata necessary fordecapsulation from the metadata processor, when necessary. The pointcloud-related metadata may be delivered to the point cloud decoder andused in a point cloud decoding procedure, or may be delivered to therenderer and used in a point cloud rendering procedure. The file/segmentdecapsulator may generate metadata related to the point cloud data.

In the video track decapsulation, a video track contained in the fileand/or segment is decapsulated. Video stream(s) including a geometryvideo, an attribute video, an occupancy map, auxiliary data, and/or meshdata are decapsulated.

In the metadata track decapsulation, a bitstream containing metadatarelated to the point cloud data and/or auxiliary data is decapsulated.

In the image decapsulation, image(s) including a geometry image, anattribute image, an occupancy map, auxiliary data and/or mesh data aredecapsulated.

The decapsulation or decapsulator according to the embodiments maydivide and parse (decapsulate) the G-PCC/V-PCC bitstream based on one ormore tracks in a file, and may also decapsulate signaling informationtherefor. In addition, the atlas stream included in the G-PCC/V-PCCbitstream may be decapsulated based on a track in the file, and relatedsignaling information may be parsed. Furthermore, an SEI message presentin the G-PCC/V-PCC bitstream may be decapsulated based on a track in thefile, and related signaling information may be also acquired.

The video decoding or video decoder 22001 performs geometry videodecompression, attribute video decompression, occupancy mapdecompression, auxiliary data decompression, and/or mesh datadecompression. The video decoder decodes the geometry video, theattribute video, the auxiliary data, and/or the mesh data in a processcorresponding to the process performed by the video encoder of the pointcloud transmission device according to the embodiments.

The image decoding or image decoder 22002 performs geometry imagedecompression, attribute image decompression, occupancy mapdecompression, auxiliary data decompression, and/or mesh datadecompression. The image decoder decodes the geometry image, theattribute image, the auxiliary data, and/or the mesh data in a processcorresponding to the process performed by the image encoder of the pointcloud transmission device according to the embodiments.

The video decoding and the image decoding according to the embodimentsmay be processed by one video/image decoder as described above, and maybe performed along separate paths as illustrated in the figure.

The video decoding and/or the image decoding may generate metadatarelated to the video data and/or the image data.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may decode the G-PCC/V-PCC bitstreamaccording to the embodiments.

In point cloud processing 22003, geometry reconstruction and/orattribute reconstruction are performed.

In the geometry reconstruction, the geometry video and/or geometry imageare reconstructed from the decoded video data and/or decoded image databased on the occupancy map, auxiliary data and/or mesh data.

In the attribute reconstruction, the attribute video and/or theattribute image are reconstructed from the decoded attribute videoand/or the decoded attribute image based on the occupancy map, auxiliarydata, and/or mesh data. According to embodiments, for example, theattribute may be a texture. According to embodiments, an attribute mayrepresent a plurality of pieces of attribute information. When there isa plurality of attributes, the point cloud processor according to theembodiments performs a plurality of attribute reconstructions.

The point cloud processor may receive metadata from the video decoder,the image decoder, and/or the file/segment decapsulator, and process thepoint cloud based on the metadata.

The point cloud rendering or point cloud renderer renders thereconstructed point cloud. The point cloud renderer may receive metadatafrom the video decoder, the image decoder, and/or the file/segmentdecapsulator, and render the point cloud based on the metadata.

The display actually displays the result of rendering on the display.

As shown in FIGS. 15 to 19, after encoding/decoding, the method/deviceaccording to the embodiments the point cloud data as shown in 15 to 19,the bitstream containing the point cloud data may be encapsulated and/ordecapsulated in the form of a file and/or a segment.

For example, a point cloud data device according to the embodiments mayencapsulate point cloud data based on a file. The file may include aV-PCC track containing parameters for a point cloud, a geometry trackcontaining geometry, an attribute track containing an attribute, and anoccupancy track containing an occupancy map.

In addition, a point cloud data reception device according toembodiments decapsulates the point cloud data based on a file. The filemay include a V-PCC track containing parameters for a point cloud, ageometry track containing geometry, an attribute track containing anattribute, and an occupancy track containing an occupancy map.

The operation described above may be performed by the file/segmentencapsulator 20004, 20005 of FIG. 20, the file/segment encapsulator21009 of FIG. 21, and the file/segment encapsulator 22000 of FIG. 22.

FIG. 23 illustrates an exemplary structure operable in connection withpoint cloud data transmission/reception methods/devices according toembodiments.

In the structure according to the embodiments, at least one of a server2360, a robot 2310, a self-driving vehicle 2320, an XR device 2330, asmartphone 2340, a home appliance 2350 and/or a head-mount display (HMD)2370 is connected to a cloud network 2300. Here, the robot 2310, theself-driving vehicle 2320, the XR device 2330, the smartphone 2340, orthe home appliance 2350 may be referred to as a device. In addition, theXR device 1730 may correspond to a point cloud data (PCC) deviceaccording to embodiments or may be operatively connected to the PCCdevice.

The cloud network 2300 may represent a network that constitutes part ofthe cloud computing infrastructure or is present in the cloud computinginfrastructure. Here, the cloud network 2300 may be configured using a3G network, 4G or Long Term Evolution (LTE) network, or a 5G network.

The server 2360 may be connected to at least one of the robot 2310, theself-driving vehicle 2320, the XR device 2330, the smartphone 2340, thehome appliance 2350, and/or the HMD 2370 over the cloud network 2300 andmay assist at least a part of the processing of the connected devices2310 to 2370.

The HMD 2370 represents one of the implementation types of the XR deviceand/or the PCC device according to the embodiments. An HMD type deviceaccording to embodiments includes a communication unit, a control unit,a memory, an I/O unit, a sensor unit, and a power supply unit.

Hereinafter, various embodiments of the devices 2310 to 2350 to whichthe above-described technology is applied will be described. The devices2310 to 2350 illustrated in FIG. 23 may be operatively connected/coupledto a point cloud data transmission and reception device according to theabove-described embodiments.

<PCC+XR>

The XR/PCC device 2330 may employ PCC technology and/or XR (AR+VR)technology, and may be implemented as an HMD, a head-up display (HUD)provided in a vehicle, a television, a mobile phone, a smartphone, acomputer, a wearable device, a home appliance, a digital signage, avehicle, a stationary robot, or a mobile robot.

The XR/PCC device 2330 may analyze 3D point cloud data or image dataacquired through various sensors or from an external device and generateposition data and attribute data about 3D points. Thereby, the XR/PCCdevice 2330 may acquire information about the surrounding space or areal object, and render and output an XR object. For example, the XR/PCCdevice 2330 may match an XR object including auxiliary information abouta recognized object with the recognized object and output the matched XRobject.

<PCC+XR+Mobile Phone>

The XR/PCC device 2330 may be implemented as a mobile phone 2340 byapplying PCC technology.

The mobile phone 2340 may decode and display point cloud content basedon the PCC technology.

<PCC+Self-Driving+XR>

The self-driving vehicle 2320 may be implemented as a mobile robot, avehicle, an unmanned aerial vehicle, or the like by applying the PCCtechnology and the XR technology.

The self-driving vehicle 2320 to which the XR/PCC technology is appliedmay represent an autonomous vehicle provided with means for providing anXR image, or an autonomous vehicle that is a target ofcontrol/interaction in the XR image. In particular, the self-drivingvehicle 2320, which is a target of control/interaction in the XR image,may be distinguished from the XR device 2330 and may be operativelyconnected thereto.

The self-driving vehicle 2320 having means for providing an XR/PCC imagemay acquire sensor information from the sensors including a camera, andoutput the generated XR/PCC image based on the acquired sensorinformation. For example, the self-driving vehicle may have an HUD andoutput an XR/PCC image thereto to provide an occupant with an XR/PCCobject corresponding to a real object or an object present on thescreen.

In this case, when the XR/PCC object is output to the HUD, at least apart of the XR/PCC object may be output to overlap the real object towhich the occupant's eyes are directed. On the other hand, when theXR/PCC object is output on a display provided inside the self-drivingvehicle, at least a part of the XR/PCC object may be output to overlapthe object on the screen. For example, the self-driving vehicle mayoutput XR/PCC objects corresponding to objects such as a road, anothervehicle, a traffic light, a traffic sign, a two-wheeled vehicle, apedestrian, and a building.

The virtual reality (VR) technology, the augmented reality (AR)technology, the mixed reality (MR) technology and/or the point cloudcompression (PCC) technology according to the embodiments are applicableto various devices.

In other words, the VR technology is a display technology that providesonly real-world objects, backgrounds, and the like as CG images. On theother hand, the AR technology refers to a technology for showing a CGimage virtually created on a real object image. The MR technology issimilar to the AR technology described above in that virtual objects tobe shown are mixed and combined with the real world. However, the MRtechnology differs from the AR technology makes a clear distinctionbetween a real object and a virtual object created as a CG image anduses virtual objects as complementary objects for real objects, whereasthe MR technology treats virtual objects as objects having the samecharacteristics as real objects. More specifically, an example of MRtechnology applications is a hologram service.

Recently, the VR, AR, and MR technologies are sometimes referred to asextended reality (XR) technology rather than being clearly distinguishedfrom each other. Accordingly, embodiments of the present disclosure areapplicable to all VR, AR, MR, and XR technologies. For suchtechnologies, encoding/decoding based on PCC, V-PCC, and G-PCCtechniques may be applied.

The PCC method/device according to the embodiments may be applied to avehicle that provides a self-driving service.

A vehicle that provides the self-driving service is connected to a PCCdevice for wired/wireless communication.

When the point cloud data transmission and reception device (PCC device)according to the embodiments is connected to a vehicle forwired/wireless communication, the device may receive and process contentdata related to an AR/VR/PCC service that may be provided together withthe self-driving service and transmit the processed content data to thevehicle. In the case where the point cloud data transmission andreception device is mounted on a vehicle, the point cloud transmittingand reception device may receive and process content data related to theAR/VR/PCC service according to a user input signal input through a userinterface device and provide the processed content data to the user. Thevehicle or the user interface device according to the embodiments mayreceive a user input signal. The user input signal according to theembodiments may include a signal indicating the self-driving service.

The method/device according to the embodiments includes a point clouddata transmission apparatus (e.g., a transmission apparatus 10000 ofFIG. 1, a transmission apparatus of FIG. 18), an encoder of thetransmission apparatus (e.g., For example, the point cloud video encoder10002 of FIG. 1, the encoder of FIG. 4, the encoder of FIG. 15), thefile encapsulator of the transmitting device (e.g., file/segmentencapsulation of the system to which the transmitting device of FIG. 20is connected) The router 20004, the pre-processor of FIG. 21, thefile/segment encapsulator 21009 of the system to which the encoder isconnected), a point cloud data receiving apparatus according toembodiments (e.g., the receiving apparatus 10005 of FIG. 1), thereceiving device of FIG. 19), the decoder of the receiving device (pointcloud video decoder 10008 of FIG. 1, the decoder of FIG. 16, the decoderof FIG. 17), the file decapsulator of the receiving device (e.g., FIG.20 Refers to the file/segment decapsulator 20005 of the system to whichthe receiving device of is connected, the processor of FIG. 22, thefile/segment decapsulator 22000 of the system to which the decoder isconnected).

Video-based point cloud compression (V-PCC) described in thisspecification is the same as visual volumetric video-based coding (V3C).The terms V-PCC and V3C according to embodiments may be usedinterchangeably and may have the same meaning.

The method/device according to the embodiments may generate andtransmit/receive 3D region information about V-PCC content for supportof spatial access of V-PCC content and 2D region related metadata (forexample, see FIGS. 25 to 45, etc.) in a video or atlas frame associatedtherewith according to a user viewport.

The method/device according to the embodiments may generate andtransmit/receive 3D region information about a point cloud in a pointcloud bitstream (for example, see FIG. 25) and 2D region relatedinformation (for example, see FIGS. 25 to 45) on a video or atlas framerelated thereto.

The method/device according to the embodiments may store andtransmit/receive 3D region information about a point cloud in a file(e.g., see FIGS. 40 and 41) and 2D region related information (e.g.,FIGS. 25 to 45) on a video or atlas frame associated therewith.

The method/device according to the embodiments may store andtransmit/receive 3D region information about a point cloud associatedwith an image item in a file (e.g., see FIG. 46) and 2D region relatedinformation on a video or atlas frame associated therewith.

The method/device according to the embodiments may group tracksincluding data related to a 3D region of point cloud data and generateand transmit/receive signaling information related thereto (see FIGS. 44and 45).

The method/device according to the embodiments may group tracksincluding data related to a 2D region and generate and transmit/receivesignaling information related thereto (see FIGS. 44 and 45, etc.).

The encoder of the V-PCC system of FIG. 20 (corresponding to the encoder10002 of FIG. 1, etc.) encodes point cloud data to generate a V-PCCbitstream (see FIG. 26, etc.). Proposed herein is a transmitter or areceiver (see FIG. 1, etc.) for providing a point cloud content servicethat the file/segment encapsulator 20004 of the V-PCC system efficientlystores the V-PCC bitstream in tracks of a file (see FIGS. 40 and 41,etc.) and provides signaling therefor.

Embodiments relate to a file storage technique for efficiently storingV-PCC bitstream in a track in a file, generating signaling informationthereon, and supporting efficient access to the stored V-PCC bitstream.Embodiments also relates to a technique for dividing and storing a V-PCCbitstream into one or more tracks in a file in relation to/combinationwith the file storage technique.

FIG. 24 illustrates a relationship between a 3D region of a point cloudand regions on a video frame according to embodiments.

A portion of a point cloud object/data rather than the entirety thereofmay be rendered or displayed on the user viewport due to the zoom-inoperation by the user or change of the user viewport. The operations maybe performed efficiently when the PCC decoder/player (FIG. 1, FIG. 20,etc.) decodes or processes video or atlas data associated with theportion of the point cloud data rendered or displayed on the userviewport. In other words, efficient operations may be ensured in termsof low latency when the operation of decoding or processing video oratlas data associated with point cloud data of a portion/region that isnot rendered or displayed is not performed.

A method/device according to embodiments may encode/transmit anddecode/receive point cloud data that changes over time, that is, dynamicpoint cloud data. For example, dynamic point cloud data is data in whichthe number of points in the point cloud changes or the position of thepoint cloud changes over time. In this case, a point cloud displayed inthe same three-dimensional region may change over time.

Accordingly, a PCC decoder/player corresponding to the method/deviceaccording to the embodiments may make a spatial access or partial accessto the point cloud data rendered/displayed on the user viewport.

Accordingly, the method/device according to the embodiments transmitsinformation for 2D region information in a video frame associated with athree-dimensional region of a point cloud that may change over time in aV-PCC bitstream or in the form of signaling or metadata.

The reception device and the renderer according to the embodiments mayrender or display a portion of a point cloud object/data rather than theentirety thereof on the user viewport due to the zoom-in operation bythe user or change of the user viewport.

The PCC decoder/player according to the embodiments may decode orprocess video or atlas data associated with the portion of the pointcloud data rendered or displayed on the user viewport for an efficientprocess.

The PCC decoder/player according to the embodiments may not perform theoperation of decoding or processing video or atlas data associated withpoint cloud data of a portion/region that is not rendered or displayed,for an efficient process.

The data 24020 associated with a 3D region 24010 of the point cloud foran object 24000 may be associated with video data 24050 of one or more2D regions 24040 within a video frame 24030.

In the case of dynamic point cloud data (data in which the number ofpoints in the point cloud changes or the location of the point cloudchanges over time), the point cloud displayed in the samethree-dimensional region may change over time.

Accordingly, in order to access the space or portion of the point clouddata rendered/displayed on the user viewport, the PCC decoder/playeraccording to the embodiments may include 2D region information about avideo frame associated with a 3D region of the point cloud that maychange over time in a V-PCC bitstream 25000 or in a file (e.g., FIG. 40)in the form of signaling or metadata.

FIG. 25 shows the structure of a bitstream containing point cloud dataaccording to embodiments.

The bitstream 25000 of FIG. 25 corresponds to the bitstream 26000 ofFIG. 26. The bitstreams of FIGS. 25 and 26 are generated by thetransmission device 10000 of FIG. 1, the point cloud video encoder 10002of FIG. 1, the encoder of FIG. 4, the encoder of FIG. 15, thetransmission device of FIG. 18, the processor 20001 of FIG. 20, andvideo/image encoder 20002 of FIG. 20, the processors 21001 to 21006 ofFIG. 21, the video/image encoder 21007, 21008 of FIG. 21, and the like.

The bitstreams of FIGS. 25 and 26 are stored in a container (the file ofFIGS. 40 and 41, etc.) by the file/segment encapsulator of FIG. 1, thefile/segment encapsulator 20004 of FIG. 20, the file/segmentencapsulator 21009 of FIG. 20, or the like.

The bitstreams of bitstreams of FIGS. 25 and 26 are transmitted by thetransmitter 10004 of FIG. 1 or the like.

The reception device 10005, the receiver 10006, or the like of FIG. 1receives the container (the file of FIGS. 40 and 41, etc.) including thebitstreams of FIGS. 25 and 26.

The bitstreams of FIGS. 25 and 26 are parsed from the container by thefile/segment decapsulator 10007 of FIG. 1, the file/segment decapsulator20005 of FIG. 20, the file/segment decapsulator 22000 of FIG. 22, or thelike.

The bitstreams of FIGS. 25 and 26 are decoded, reconstructed, andprovided to the user by the point cloud video decoder 10008 of FIG. 1,the decoder of FIG. 16, the decoder of FIG. 17, the reception device ofFIG. 19, the video/image decoder 20006 of FIG. 20, the video/imagedecoders 22001 and 22002 of FIG. 22, the processor 22003 of FIG. 22, orthe like.

A sample stream V-PCC unit included in the bitstream 25000 for pointcloud data according to embodiments may include a V-PCC unit size 25010and a V-PCC unit 25020.

The terms employed in this document are defined as follows: VPS (V-PCCparameter set); AD (Atlas data); OVD (Occupancy video data); GVD(Geometry video data); AVD (Attribute video data).

Each V-PCC unit 25020 may include a V-PCC unit header 25030 and a V-PCCunit payload 25040. The V-PCC unit header 25030 may describe a V-PCCunit type. The V-PCC unit header of attribute video data may describe anattribute type, an index thereof, multiple instances of the sameattribute type supported, and the like.

The unit payloads 25050, 25060, and 25070 of occupancy, geometry andattribute video data may correspond to video data units. For example,the occupancy video data, geometry video data, and attribute video data25050, 25060, and 25070 may be HEVC NAL units. Such video data may bedecoded by a video decoder according to embodiments.

FIG. 26 shows the structure of a bitstream containing point cloud dataaccording to embodiments.

FIG. 26 shows the structure of a bitstream containing point cloud datato be encoded or decoded according to embodiments, as described withreference to FIGS. 18 to 25.

The method/device according to the embodiments generates a bitstream fora dynamic point cloud object. In this regard, a file format for thebitstream is proposed, and a signaling scheme therefor is provided.

The method/device according to the embodiments includes a transmitter, areceiver, and/or a processor for providing a point cloud content serviceof efficiently storing a V-PCC (=V3C) bitstream in a track of a file andproviding signaling therefor.

The method/device according to the embodiments provides a data formatfor storing a V-PCC bitstream containing point cloud data. Accordingly,the reception method/device according to the embodiments provides a datastorage and signaling method for receiving point cloud data andefficiently accessing the point cloud data. Therefore, based on thestorage technique for a file containing point cloud data for efficientaccess, the transmitter and/or the receiver may provide a point cloudcontent service.

The method/device according to the embodiments efficiently stores apoint cloud bitstream (V-PCC bitstream) in a track of a file. Itgenerates signaling information about an efficient storage technique andstores the same in the file. To support efficient access to the V-PCCbitstream stored in the file, a technique for partitioning and storingthe V-PCC bitstream into one or more tracks in the file may be providedin addition to (or by modifying/in combination with) the file storagetechnique according to the embodiments.

The terms employed in this document are defined as follows:

VPS: V-PCC parameter set; AD: Atlas data; OVD: Occupancy video data;GVD: Geometry video data; AVD: Attribute video data; ACL: Atlas CodingLayer; AAPS: Atlas adaptation parameter set; ASPS: Atlas sequenceparameter set, which may be a syntax structure containing syntaxelements according to embodiments that apply to zero or more entirecoded atlas sequences (CASs) as determined by the content of a syntaxelement found in the ASPS referred to by a syntax element found in eachtile group header.

AFPS: Atlas frame parameter set, which may include a syntax structurecontaining syntax elements that apply to zero or more entire coded atlasframes as determined by the content of a syntax element found in thetile group header.

SEI: Supplemental enhancement information.

Atlas: A collection of 2D bounding boxes, for example, patches projectedinto a rectangular frame that corresponds to a 3D bounding box in 3Dspace. Atlas may represent a subset of a point cloud.

Atlas sub-bitstream: an extracted sub-bitstream from the V-PCC bitstreamcontaining a part of an atlas NAL bitstream.

V-PCC content: A point cloud encoded based on V-PCC (V3C).

V-PCC track: A volumetric visual track which carries the atlas bitstreamof the V-PCC bitstream.

V-PCC component track: A video track which carries 2D video encoded datafor any of the occupancy map, geometry, or attribute component videobitstreams of the V-PCC bitstream.

Embodiments for supporting partial access of a dynamic point cloudobject will be described. Embodiments include atlas tile groupinformation associated with some data of a V-PCC object included in eachspatial region at a file system level. Further, embodiments include anextended signaling scheme for label and/or patch information included ineach atlas tile group.

FIG. 26 shows a structure of a point cloud bitstream included in datatransmitted and received by the methods/devices according to theembodiments.

A method of compressing and decompressing point cloud data according toembodiments refers to volumetric encoding and decoding of point cloudvisual information.

A point cloud bitstream (which may be referred to as a V-PCC bitstreamor V3C bitstream) 26000 containing a coded point cloud sequence (CPCS)may include sample stream V-PCC units 26010. The sample stream V-PCCunits 26010 may carry V-PCC parameter set (VPS) data 26020, an atlasbitstream 26030, a 2D video encoded occupancy map bitstream 26040, a 2Dvideo encoded geometry bitstream 26050, and zero or one or more 2D videoencoded attribute bitstreams 26060.

The point cloud bitstream 26000 may include a sample stream VPCC header26070.

ssvh_unit_size_precision_bytes_minus1: A value obtained by adding 1 tothis value specifies the precision, in bytes, of the ssvu_vpcc_unit_sizeelement in all sample stream V-PCC units.ssvh_unit_size_precision_bytes_minus1 may be in the range of 0 to 7.

The syntax 26080 of the sample stream V-PCC unit 26010 is configured asfollows. Each sample stream V-PCC unit may include a type of one ofV-PCC units of VPS, AD, OVD, GVD, and AVD. The content of each samplestream V-PCC unit may be associated with the same access unit as theV-PCC unit included in the sample stream V-PCC unit.

ssvu_vpcc_unit_size: specifies the size, in bytes, of the subsequentvpcc_unit. The number of bits used to represent ssvu_vpcc_unit_size isequal to (ssvh_unit_size_precision_bytes_minus1+1)*8.

The method/device according to the embodiments receives the bitstream ofFIG. 26 containing the encoded point cloud data, and generates a file asshown in FIGS. 40 and 41 through the encapsulator 20004 or 21009.

The method/device according to the embodiments receives a file as shownin FIGS. 40 and 41 and decodes point cloud data through the decapsulator22000 or the like.

The VPS 26020 and/or AD 26030 are encapsulated in track-4 (V3C track)40030).

The OVD 26040 is encapsulated in track-2 (occupancy track) 40010.

The GVD 26050 is encapsulated in track-3 (geometry track) 40020.

The AVD 26060 is encapsulated in track-1 (attribute track) 40000.

FIG. 27 shows a V-PCC unit and a V-PCC unit header according toembodiments.

FIG. 27 shows the syntaxes of the V-PCC unit 25020 and the V-PCC unitheader 25030 described above with reference to FIG. 25.

A V-PCC bitstream according to embodiments may contain a series of V-PCCsequences.

A vpcc unit type with a value of vuh_unit_type equal to VPCC_VPS may beexpected to be the first V-PCC unit type in a V-PCC sequence. All otherV-PCC unit types follow this unit type without any additionalrestrictions in their coding order. A V-PCC unit payload of a V-PCC unitcarrying occupancy video, attribute video, or geometry video is composedof one or more NAL units.

A VPCC unit may include a header and a payload.

The VPCC unit header may include the following information based on theVUH unit type.

vuh_unit_type indicates the type of the V-PCC unit 25020 as follows.

vuh_unit_type Identifier V-PCC Unit Type Description 0 VPCC_VPS V-PCCparameter set V-PCC level parameters 1 VPCC_AD Atlas data Atlasinformation 2 VPCC_OVD Occupancy Video Data Occupancy information 3VPCC_GVD Geometry Video Data Geometry information 4 VPCC_AVD AttributeVideo Data Attribute information 5 . . . 31 VPCC_RSVD Reserved —

When vuh_unit_type indicates attribute video data (VPCC_AVD), geometryvideo data (VPCC_GVD), occupancy video data (VPCC_OVD), or atlas data(VPCC_AD), vuh_vpcc_parameter_set ID and vuh_atlas_id is carried in theunit header. A parameter set ID and an atlas ID associated with theV-PCC unit may be delivered.

When the unit_type is atlas video data, the header of the unit may carryan attribute index (vuh_attribute_index), an attribute partition index(vuh_attribute_partition_index), a map index (vuh_map_index), and anauxiliary video flag (vuh_auxiliary_video_flag).

When the unit type is geometry video data, vuh_map_index andvuh_auxiliary_video_flag may be carried.

When the unit_type is occupancy video data or atlas data, the header ofthe unit may contain additional reserved bits.

vuh_vpcc_parameter_set_id specifies the value ofvps_vpcc_parameter_set_id for the active V-PCC VPS. Through thevpcc_parameter_set_id in the header of the current V-PCC unit, the ID ofthe VPS parameter set may be known and the relationship between theV-PCC unit and the V-PCC parameter set may be announced.

vuh_atlas_id specifies the index of the atlas that corresponds to thecurrent V-PCC unit. Through the vuh_atlas_id in the header of thecurrent V-PCC unit, the index of the atlas may be known, and the atlascorresponding to the V-PCC unit may be announced.

vuh_attribute_index indicates the index of the attribute data carried inthe Attribute Video Data unit.

vuh_attribute_partition_index indicates the index of the attributedimension group carried in the Attribute Video Data unit.

vuh_map_index indicates, when present, the map index of the currentgeometry or attribute stream.

vuh_auxiliary_video_flag equal to 1 indicates that the associatedgeometry or attribute video data unit is a RAW and/or EOM coded pointsvideo only. vuh_auxiliary_video_flag equal to 0 indicates that theassociated geometry or attribute video data unit may contain RAW and/orEOM coded points.

FIG. 28 shows the payload of a V-PCC unit according to embodiments.

FIG. 28 shows the syntax of the V-PCC unit payload 25040.

When vuh_unit_type is V-PCC parameter set (VPCC_VPS), the V-PCC unitpayload contains vpcc_parameter_set( ).

When vuh_unit_type is V-PCC atlas data (VPCC_AD), the V-PCC unit payloadcontains atlas_sub_bitstream( ).

When vuh_unit_type is V-PCC accumulating video data (VPCC_OVD),geometric video data (VPCC_GVD), or attribute video data (VPCC_AVD), theV-PCC unit payload contains video_sub_bitstream( ).

FIG. 29 shows a V-PCC parameter set according to embodiments.

FIG. 29 shows the syntax of a parameter set when the payload 25040 ofthe unit 25020 of the bitstream according to the embodiments containsthe parameter set as shown in FIG. 28.

The VPS of FIG. 29 may include the following elements.

profile_tier_level( ) specifies restrictions on the bitstreams and hencelimits on the capabilities needed to decode the bitstreams. Profiles,tiers, and levels may also be used to indicate interoperability pointsbetween individual decoder implementations.

vps_vpcc_parameter_set_id may provide an identifier for the V-PCC VPSfor reference by other syntax elements.

sps_bounding box_present_flag is a flag indicating whether there isinformation on the overall bounding box of a point cloud object/contentin the bitstream (which may be a bounding box that may include theentirety of a bounding box that changes over time.sps_bounding_box_present_flag equal to 1 indicates overall bounding boxoffset and the size information of point cloud content carried in thisbitstream).

When sps_bounding_box_present_flag has a specific value, the followingbounding box elements are included in the VPS.

sps_bounding_box_offset_x indicates the x offset of overall bounding boxoffset and the size information of point cloud content carried in thisbitstream in the Cartesian coordinates. When not present, the value ofsps_bounding_box_offset_x may be inferred to be 0.

sps_bounding_box_offset_y indicates the y offset of overall bounding boxoffset and the size information of point cloud content carried in thisbitstream in the Cartesian coordinates. When not present, the value ofsps_bounding_box_offset_y may be inferred to be 0.

sps_bounding_box_offset_z indicates the z offset of overall bounding boxoffset and the size information of point cloud content carried in thisbitstream in the Cartesian coordinates. When not present, the value ofsps_bounding_box_offset_z may be inferred to be 0.

sps_bounding_box_size width indicates the width of overall bounding boxoffset and the size information of point cloud content carried in thisbitstream in the Cartesian coordinates. When not present, the value ofsps_bounding_box_size width may be inferred to be 1.

sps_bounding_box_size_height indicates the height of overall boundingbox offset and the size information of point cloud content carried inthis bitstream in the Cartesian coordinates. When not present, the valueof sps_bounding_box_size_height may be inferred to be 1.

sps_bounding_box_size_depth indicates the depth of overall bounding boxoffset and the size information of point cloud content carried in thisbitstream in the Cartesian coordinates. When not present, the value ofsps_bounding_box_size_depth may be inferred to be 1.

sps_bounding_box_changed_flag is a flag indicating whether the boundingbox of point cloud data contained in the bitstream changes over time.The flag equal to 1 may indicate that the bounding box of the pointcloud data changes over time.

sps_bounding_box_info_flag is a flag indicating whether SEI includingbounding box information about the point cloud data is contained in thebitstream. The flag equal to 1 may indicate that 3D bounding box SEI(see FIG. 35, etc.) including bounding box information about the pointcloud data is contained in the bitstream. In this case, a PCC playcorresponding to the method/device according to the embodiments mayinform that the information included in the SEI can be acquired andused.

vps_atlas_count_minus1 plus 1 indicates the total number of supportedatlases in the current bitstream.

Depending on the number of atlases, the following parameters may befurther included in the parameter set.

vps_frame_width[j] indicates the V-PCC frame width in terms of integerluma samples for the atlas with index j. This frame width is the nominalwidth that is associated with all V-PCC components for the atlas withindex j.

vps_frame_height[j] indicates the V-PCC frame height in terms of integerluma samples for the atlas with index j. This frame height is thenominal height that is associated with all V-PCC components for theatlas with index j.

vps_map_count_minus1[j] plus 1 indicates the number of maps used forencoding the geometry and attribute data for the atlas with index j.

When vps_map_count_minus1[j] is greater than 0, the following parametersmay be further included in the parameter set.

Depending on the value of vps_map_count_minus1[j], the followingparameters may be further included in the parameter set.

vps_multiple_map_streams_present_flag[j] equal to 0 indicates that allgeometry or attribute maps for the atlas with index j are placed in asingle geometry or attribute video stream, respectively.vps_multiple_map_streams_present_flag[j] equal to 1 indicates that allgeometry or attribute maps for the atlas with index j are placed inseparate video streams.

If vps_multiple_map_streams_present_flag[j] indicates 1,vps_map_absolute_coding_enabled_flag[j][i] may be further included inthe parameter set. Otherwise, vps_map_absolute_coding_enabled_flag[j][i]may have a value of 1.

vps_map_absolute_coding_enabled_flag[j][i] equal to 1 indicates that thegeometry map with index i for the atlas with index j is coded withoutany form of map prediction. vps_map_absolute_coding_enabled_flag[j][i]equal to 0 indicates that the geometry map with index i for the atlaswith index j is first predicted from another, earlier coded map, priorto coding.

vps_map_absolute_coding_enabled_flag[j][0] equal to 1 indicates that thegeometry map with index 0 is coded without map prediction.

If vps_map_absolute_coding_enabled_flag[j][i] is 0 and i is greater than0, vps_map_predictor_index_diff[j][i] may be further included in theparameter set. Otherwise, vps_map_predictor_index_diff[j][i] may be 0.

vps_map_predictor_index_diff[j][i] is used to compute the predictor ofthe geometry map with index i for the atlas with index j whenvps_map_absolute_coding_enabled_flag[j][i] is equal to 0.

vps_auxiliary_video_present_flag[j] equal to 1 indicates that auxiliaryinformation for the atlas with index j, i.e. RAW or EOM patch data, maybe stored in a separate video stream, referred to as the auxiliary videostream. vps_auxiliary_video_present_flag[j] equal to 0 indicates thatauxiliary information for the atlas with index j is not be stored in aseparate video stream.

vps_raw_patch_enabled_flag[j] equal to 1 indicates that patches with RAWcoded points for the atlas with index j may be present in the bitstream.

When vps_raw_patch_enabled_flag[j] has a specific value, the followingelements are included in the VPS.

vps_raw_separate_video_present_flag[j] equal to 1 indicates that RAWcoded geometry and attribute information for the atlas with index j maybe stored in a separate video stream

occupancy_information( ) includes occupancy video related parametersets.

geometry_information( ) includes geometry video related parameter sets.

attribute_information( ) includes attribute video related parametersets.

vps_extension_present_flag_equal to 1 specifies that the syntax elementvps_extension_length is present in vpcc_parameter_set syntax structure.vps_extension_present_flag equal to 0 specifies that syntax elementvps_extension_length is not present.

vps_extension_length_minus1 plus 1 specifies the number ofvps_extension_data_byte elements that follow this syntax element.

Depending on vps_extension_length_minus1, extension data may be furtherincluded in the parameter_set.

vps_extension_data byte may have any value that may be included throughextension.

FIG. 30 shows the structure of an atlas bitstream according toembodiments.

FIG. 30 shows an example in which the payload 25040 of the unit 25020 ofthe bitstream 25000 of FIG. 25 carries an atlas sub-bitstream 30000

The V-PCC unit payload of the V-PCC unit carrying the atlassub-bitstream may include one or more sample stream NAL units 30010.

The atlas sub-bitstream 30000 according to the embodiments may include asample stream NAL header 30020 and one or more sample stream NAL units30010.

The sample stream NAL header 30020 may includessnh_unit_size_precision_bytes_minus1.ssnh_unit_size_precision_bytes_minus1 plus 1 specifies the precision, inbytes, of the ssnu_nal_unit_size element in all sample stream NAL units.ssnh_unit_size_precision_bytes_minus1 may be in the range of 0 to 7.

The sample stream NAL unit 30010 may include ssnu_nal_unit_size.

ssnu_nal_unit_size specifies the size, in bytes, of the subsequentNAL_unit. The number of bits used to represent ssnu_nal_unit_size may beequal to (ssnh_unit_size_precision_bytes_minus1+1)*8.

Each sample stream NAL unit may include an atlas sequence parameter set(ASPS) 30030, an atlas frame parameter set (AFPS) 30040, one or morepieces of atlas tile group information 30050, and one or more pieces ofsupplemental enhancement information (SEI) 30060, each of which will bedescribed below. According to embodiments, the atlas tile group may bereferred to as an atlas tile.

The NAL unit may include nal_unit_header( ) and NumBytesInRbsp.

NumBytesInRbsp indicates bytes corresponding to the payload of the NALunit, and the initial value thereof is set to 0.

nal_unit_header( ) may include nal_forbidden_zero_bit, nal_unit_type,nal_layer_id, and nal_temporal_id_plus1.

nal forbidden zero bit is a field used for error detection of the NALunit and should be 0.

nal_unit_type indicates the type of the RBSP data structure included inthe NAL unit as shown in FIG. 32.

nal_layer_id specifies the identifier of the layer to which an ACL NALunit belongs or the identifier of a layer to which a non-ACL NAL unitapplies.

nal_temporal_id_plus1 minus 1 specifies a temporal identifier for theNAL unit.

The nal_unit_type may include the following types:

NAL_TRAIL: A coded tile group of a non-TSA, non STSA trailing atlasframe may be included in the NAL unit. The RBSP syntax structure of theNAL unit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ).The type class of the NAL unit is ACL. According to embodiments, a tilegroup may correspond to a tile.

NAL TSA: A coded tile group of a TSA atlas frame may be included in theNAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_STSA: A coded tile group of an STSA atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RADL: A coded tile group of an RADL atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RASL: A coded tile group of an RASL atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or aatlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_SKIP: A coded tile group of a skipped atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RSV_ACL_6 to NAL_RSV_ACL_9: Reserved non-IRAP ACL NAL unit types maybe included in the NAL unit. The type class of the NAL unit is ACL.

NAL_BLA_W_LP, NAL_BLA_W_RADL, NAL_BLA_N_LP: A coded tile group of a BLAatlas frame may be included in the NAL unit. The RBSP syntax structureof the NAL unit is atlas_tile_group_layer_rbsp( ) oratlas_tile_layer_rbsp( ). The type class of the NAL unit is ACL.

NAL_GBLA_W_LP, NAL_GBLA_W_RADL, NAL_GBLA_N_LP: A coded tile group of aGBLA atlas frame may be included in the NAL unit. The RBSP syntaxstructure of the NAL unit is atlas_tile_group_layer_rbsp( ) oratlas_tile_layer_rbsp( ). The type class of the NAL unit is ACL.

NAL_IDR_W_RADL, NAL_IDR_N_LP: A coded tile group of an IDR atlas framemay be included in the NAL unit. The RBSP syntax structure of the NALunit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). Thetype class of the NAL unit is ACL.

NAL_GIDR_W_RADL, NAL_GIDR_N_LP: A coded tile group of a GIDR atlas framemay be included in the NAL unit. The RBSP syntax structure of the NALunit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). Thetype class of the NAL unit is ACL.

NAL_CRA: A coded tile group of a CRA atlas frame may be included in theNAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_GCRA: A coded tile group of a GCRA atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_IRAP_ACL_22, NAL_IRAP_ACL_23: Reserved TRAP ACL NAL unit types maybe included in the NAL unit. The type class of the NAL unit is ACL.

NAL_RSV_ACL_24 to NAL_RSV_ACL_31: Reserved non-IRAP ACL NAL unit typesmay be included in the NAL unit. The type class of the NAL unit is ACL.

NAL_ASPS: An atlas sequence parameter set may be included in the NALunit. The RBSP syntax structure of the NAL unit isatlas_sequence_parameter_set_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_AFPS: An atlas frame parameter set may be included in the NAL unit.The RBSP syntax structure of the NAL unit isatlas_frame_parameter_set_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_AUD: An access unit delimiter may be included in the NAL unit. TheRBSP syntax structure of the NAL unit is access_unit_delimiter_rbsp( ).The type class of the NAL unit is non-ACL.

NAL_VPCC_AUD: A V-PCC access unit delimiter may be included in the NALunit. The RBSP syntax structure of the NAL unit isaccess_unit_delimiter_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_EOS: The NAL unit type may be end of sequence. The RBSP syntaxstructure of the NAL unit is end_of_seq_rbsp( ). The type class of theNAL unit is non-ACL.

NAL_EOB: The NAL unit type may be end of bitstream. The RBSP syntaxstructure of the NAL unit is end of atlas_sub_bitstream_rbsp( ). Thetype class of the NAL unit is non-ACL.

NAL_FD Filler: The NAL unit type may be filler_data_rbsp( ). The typeclass of the NAL unit is non-ACL.

NAL_PREFIX_NSEI, NAL_SUFFIX_NSEI: The NAL unit type may be non-essentialsupplemental enhancement information. The RBSP syntax structure of theNAL unit is sei_rbsp( ). The type class of the NAL unit is non-ACL.

NAL_PREFIX_ESEI, NAL_SUFFIX_ESEI: The NAL unit type may be essentialsupplemental enhancement information. The RBSP syntax structure of theNAL unit is sei_rbsp( ). The type class of the NAL unit is non-ACL.

NAL_AAPS: The NAL unit_type may be atlas adaptation parameter set. TheRBSP syntax structure of the NAL unit isatlas_adaptation_parameter_set_rbsp( ). The type class of the NAL unitis non-ACL.

NAL_RSV_NACL_44 to NAL_RSV_NACL_47: The NAL unit type may be reservednon-ACL NAL unit types. The type class of the NAL unit is non-ACL.

NAL_UNSPEC_48 to NAL_UNSPEC_63: The NAL unit type may be unspecifiednon-ACL NAL unit types. The type class of the NAL unit is non-ACL.

FIG. 31 shows an atlas sequence parameter set according to embodiments.

FIG. 31 shows the syntax of an RBSP data structure included in a NALunit when the NAL unit type is atlas sequence parameter.

Each sample stream NAL unit may contain one of an atlas parameter set,for example, ASPS, AAPS, or AFPS, one or more atlas tile group about,and SEIs.

The ASPS may contain syntax elements that apply to zero or more entirecoded atlas sequences (CASs) as determined by the content of a syntaxelement found in the ASPS referred to by a syntax element found in eachtile group header.

The ASPS may include the following elements.

asps_atlas_sequence_parameter_set_id may provide an identifier for theatlas sequence parameter set for reference by other syntax elements.

asps_frame_width indicates the atlas frame width in terms of integerluma samples for the current atlas.

asps_frame_height indicates the atlas frame height in terms of integerluma samples for the current atlas.

asps_log2_patch_packing_block_size specifies the value of the variablePatchPackingBlockSize that is used for the horizontal and verticalplacement of the patches within the atlas.

asps_log2_max_atlas_frame_order_cnt_lsb_minus4 specifies the value ofthe variable MaxAtlasFrmOrderCntLsb that is used in the decoding processfor the atlas frame order count.

asps_max_dec_atlas_frame_buffering_minus1 plus 1 specifies the maximumrequired size of the decoded atlas frame buffer for the CAS in units ofatlas frame storage buffers.

asps_long_term_ref_atlas_frames_flag_equal to 0 specifies that no longterm reference atlas frame is used for inter prediction of any codedatlas frame in the CAS. asps_long_term_ref_atlas_frames_flag_equal to 1specifies that long term reference atlas frames may be used for interprediction of one or more coded atlas frames in the CAS.

asps_num_ref_atlas_frame_lists_in_asps specifies the number of theref_list_struct(rlsIdx) syntax structures included in the atlas sequenceparameter set.

ref_list_struct(i) may be included in the atlas sequence parameter setaccording to the value of asps_num_ref_atlas_frame_lists_in_asps.

asps_use_eight_orientations_flag_equal to 0 specifies that the patchorientation index for a patch with index j in a frame with index i,pdu_orientation_index[i][j], is in the range of 0 to 1, inclusive.asps_use_eight_orientations_flag equal to 1 specifies that the patchorientation index for a patch with index j in a frame with index i,pdu_orientatio_n index[i][j], is in the range of 0 to 7, inclusive.

asps_45degree_projection_patch_present_flag equal to 0 specifies thatthe patch projection information is not signaled for the current atlastile group. asps_45degree_projection_present_flag equal to 1 specifiesthat the patch projection information is signaled for the current atlastile group.

When atgh_type is not SKIP TILE GRP, the following elements may beincluded in the atlas tile group (or tile) header.

asps_normal_axis_limits_quantization_enabled_flag equal to 1 specifiesthat quantization parameters shall be signalled and used for quantizingthe normal axis related elements of a patch data unit, a merge patchdata unit, or an inter patch data unit. Ifasps_normal_axis_limits_quantization_enabled_flag is equal to 0, then noquantization is applied on any normal axis related elements of a patchdata unit, a merge patch data unit, or an inter patch data unit.

When asps_normal_axis_limits_quantization_enabled_flag is 1,atgh_pos_min_z_quantizer may be included in the atlas tile group (ortile) header.

asps_normal_axis_max_delta_value_enabled_flag equal to 1 specifies thatthe maximum nominal shift value of the normal axis that may be presentin the geometry information of a patch with index i in a frame withindex j will be indicated in the bitstream for each patch data unit, amerge patch data unit, or an inter patch data unit. Ifasps_normal_axis_max_delta_value_enabled_flag is equal to 0, then themaximum nominal shift value of the normal axis that may be present inthe geometry information of a patch with index i in a frame with index jshall not be indicated in the bitstream for each patch data unit, amerge patch data unit, or an inter patch data unit.

When asps_normal_axis_max_delta_value_enabled_flag is equal to 1,atgh_pos_delta_max_z_quantizer may be included in the atlas tile group(or tile) header.

asps_remove_duplicate_point_enabled_flag equal to 1 indicates thatduplicated points are not econstructed for the current atlas, where aduplicated point is a point with the same 2D and 3D geometry coordinatesas another point from a lower index map.asps_remove_duplicate_point_enabled_flag equal to 0 indicates that allpoints are reconstructed.

asps_max_dec_atlas_frame_buffering_minus1 plus 1 specifies the maximumrequired size of the decoded atlas frame buffer for the CAS in units ofatlas frame storage buffers.

asps_pixel_deinterleaving_flag equal to 1 indicates that the decodedgeometry and attribute videos for the current atlas contain spatiallyinterleaved pixels from two maps. asps_pixel_deinterleaving_flag equalto 0 indicates that the decoded geometry and attribute videoscorresponding to the current atlas contain pixels from only a singlemap.

asps_patch_precedence_order_flag equal to 1 indicates that patchprecedence for the current atlas is the same as the decoding order.asps_patch_precedence_order_flag equal to 0 indicates that patchprecedence for the current atlas is the reverse of the decoding order.

asps_patch_size_quantizer_present_flag equal to 1 indicates that thepatch size quantization parameters are present in an atlas tile groupheader. asps_patch_size_quantizer_present flag equal to 0 indicates thatthe patch size quantization parameters are not present.

When asps_patch_size_quantizer_present_flag is equal to 1,atgh_patch_size_x_info_quantizer and atgh_patch_size_y info quantizermay be included in the atlas tile group (or tile) header.

asps_enhanced_occupancy_map_for_depth_flag equal to 1 indicates that thedecoded occupancy map video for the current atlas contains informationrelated to whether intermediate depth positions between two depth mapsare occupied. asps_eom_patch_enabled_flag equal to 0 indicates that thedecoded occupancy map video does not contain information related towhether intermediate depth positions between two depth maps areoccupied.

When asps_enhanced_occupancy_map_for_depth_flag orasps_point_local_reconstruction_enabled_flag is equal to 1,asps_map_count_minus1 may be included in the ASPS.

asps_point_local_reconstruction_enabled_flag equal to 1 indicates thatpoint local reconstruction mode information may be present in thebitstream for the current atlas.asps_point_local_reconstruction_enabled_flag equal to 0 indicates thatno information related to the point local reconstruction mode is presentin the bitstream for the current atlas.

When asps_point_local_reconstruction_enabled_flag is equal to 1,asps_point_local_reconstruction_information may be carried in the atlassequence parameter set.

asps_map_count_minus1 plus 1 indicates the number of maps that may beused for encoding the geometry and attribute data for the current atlas.

asps_enhanced_occupancy_map_fix_bit_count_minus1 plus 1 indicates thesize in bits of the EOM codeword.

When asps_enhanced_occupancy_map_for_depth_flag andasps_map_count_minus1 are set to 0,asps_enhanced_occupancy_map_fix_bit_count_minus1 may be included in theASPS.

asps_surface_thickness_minus1 plus 1 specifies the maximum absolutedifference between an explicitly coded depth value and interpolateddepth value when asps_pixel_deinterleaving_enabled_flag (orasps_pixel_interleaving_flag) orasps_point_local_reconstruction_enabled_flag is equal to 1.

When asps_pixel_interleaving_flag orasps_point_local_reconstruction_enabled_flag is equal to 1, theasps_surface_thickness_minus1 may be included in the ASPS.

asps_pixel_interleaving_flag may correspond toasps_map_pixel_deinterleaving_flag.

asps_map_pixel_deinterleaving_flag[i] equal to 1 indicates that decodedgeometry and attribute videos corresponding to map with index i in thecurrent atlas contain spatially interleaved pixels corresponding to twomaps. asps mappixel deinterleaving flag[i] equal to 0 indicates thatdecoded geometry and attribute videos corresponding to map index i inthe current atlas contain pixels corresponding to a single map. When notpresent, the value of asps_map_pixel_deinterleaving_flag[i] may beinferred to be 0.

aspspoint local reconstruction enabled flag equal to 1 indicates thatpoint local reconstruction mode information may be present in thebitstream for the current atlas. aspspoint local reconstruction enabledflag equal to 0 indicates that no information related to the point localreconstruction mode is present in the bitstream for the current atlas.

asps vui_parameters_present flag equal to 1 specifies that thevui_parameters( )) syntax structure is present. aspsvuiparameterspresent flag equal to 0 specifies that the vui_parameters()) syntax structure is not present.

asps extension flag equal to 0 specifies that no asps extension dataflag syntax elements are present in the ASPS RBSP syntax structure.

asps extension data flag Indicates that data for extension is includedin the ASPS RB SP syntax structure.

rbsp trailing bits is used to fill the remaining bits with 0 for bytealignment after adding 1, which is a stop bit, to indicate the end ofRBSP data.

FIG. 32 shows an atlas frame parameter_set according to embodiments.

FIG. 32 shows the syntax of an atlas frame parameter_set contained inthe NAL unit when the NAL unit_type is NAL_AFPS.

The atlas frame parameter_set (AFPS) contains a syntax structurecontaining syntax elements that apply to all zero or more entire codedatlas frames.

afps_atlas_frame_parameter_set_id_identifies the atlas frame parameterset for reference by other syntax elements. An identifier that may bereferred to by other syntax elements may be provided through the AFPSatlas frame parameter set.

afps_atlas_sequence_parameter_set_id specifies the value ofasps_atlas_sequence_parameter_set_id for the active atlas sequenceparameter set.

atlas_frame_tile_information( ) will be described with reference to FIG.33.

afps_num_ref_idx_default_active_minus1 plus 1 specifies the inferredvalue of the variable NumRefIdxActive for the tile group withatgh_num_ref_idx_active_override_flag equal to 0.

afps_additional_lt_afoc_lsb_len specifies the value of the variableMaxLtAtlasFrmOrderCntLsb that is used in the decoding process forreference atlas frame lists.

afps_2d_pos_x_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_2d_pos_x[j] of a patch with indexj in an atlas tile group that refers toafps_atlas_frame_parameter_set_id.

afps_2d_pos_y_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_2d_pos_y[j] of a patch with indexj in an atlas tile group that refers toafps_atlas_frame_parameter_set_id.

afps_3d_pos_x_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_3d_pos_x[j] of patch with index jin an atlas tile group that refers to afps_atlas_frame_parameter_set_id.

afps_3d_pos_y_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_3d_pos_y[j] of patch with index jin an atlas tile group that refers to afps_atlas_frame_parameter_set_id.

afps_lod_bit count specifies the number of bits in the fixed-lengthrepresentation of pdu_lod[j] of a patch with index j in an atlas tilegroup that refers to afps_atlas_frame_parameter_set_id.

afps_override_eom_for_depth_flag_equal to 1 indicates that the values ofafps_eom_number_of_patch_bit_count_minus1 andafps_eom_max_bit_count_minus1 are explicitly present in the bitstream.afps_override_eom_for_depth_flag equal to 0 indicates that the values ofafps_eom_number_of_patch_bit_count_minus1 andafps_eom_max_bit_count_minus1 are implicitly derived.

afps_eom_number_of_patch_bit_count_minus1 plus 1 specifies the number ofbits used to represent the number of geometry patches associated withthe current EOM attribute patch.

afps_eom_max_bit_count_minus1 plus 1 specifies the number of bits usedto represent the number of EOM points per geometry patch associated withthe current EOM attribute patch.

afps_raw_3d_pos_bit_count_explicit_mode_flag equal to 1 indicates thatthe bit count for rpdu_3d_pos_x, rpdu_3d_pos_y, and rpdu_3d_pos_z isexplicitely coded in an atlas tile group header that refers toafps_atlas_frame_parameter_set_id.

afps_extension_flag equal to 0 specifies that noafps_extension_data_flag syntax elements are present in the AFPS RBSPsyntax structure.

afps_extension_data_flag may contain extension related data.

FIG. 33 shows atlas_frame_tile_information according to embodiments.

FIG. 33 shows the syntax of atlas_frame_tile_information included inFIG. 32;

afti_single_tile_in_atlas_frame_flag equal to 1 specifies that there isonly one tile in each atlas frame referring to the AFPS.afti_single_tile_in_atlas_frame_flag equal to 0 specifies that there ismore than one tile in each atlas frame referring to the AFPS.

afti_uniform_tile_spacing_flag_equal to 1 specifies that tile column androw boundaries are distributed uniformly across the atlas frame andsignaled using the syntax elements, afti_tile_cols_width_minus1 andafti_tile_rows_height_minus1, respectively.afti_uniform_tile_spacing_flag_equal to 0 specifies that tile column androw boundaries may or may not be distributed uniformly across the atlasframe and are signaled using the syntax elementsafti_num_tile_columns_minus1 and afti_num_tile_rows_minus1 and a list ofsyntax element pairs afti_tile_column_width_minus1 [i] andafti_tile_row_height_minus1[i].

afti_tile_cols_width_minus1 plus 1 specifies the width of the tilecolumns excluding the right-most tile column of the atlas frame in unitsof 64 samples when afti_uniform_tile_spacing_flag is equal to 1.

afti_tile_rows_height_minus1 plus 1 specifies the height of the tilerows excluding the bottom tile row of the atlas frame in units of 64samples when afti_uniform_tile_spacing_flag is equal to 1.

When afti_uniform_tile_spacing_flag is not equal to 1, the followingelements are included in the atlas frame tile information.

afti_num_tile_columns_minus1 plus 1 specifies the number of tile columnspartitioning the atlas frame when afti_uniform_tile_spacing_flag isequal to 0.

afti_num_tile_rows_minus1 plus 1 specifies the number of tile rowspartitioning the atlas frame when pti_uniform_tile_spacing_flag is equalto 0.

afti_tile_column_width_minus1[i] plus 1 specifies the width of the i-thtile column in units of 64 samples.

afti_tile_column_width_minus1[i] is included in the atlas frame tileinformation according to the value of afti_num_tile_columns_minus1.

afti_tile_row_height_minus1 [i] plus 1 specifies the height of the i-thtile row in units of 64 samples.

afti_tile_row_height_minus1 [i] is included in the atlas frame tileinformation according to the value of afti_num_tile_rows_minus1.

afti_single_tile_per_tile_group_flag equal to 1 specifies that each tilegroup (or tile) that refers to this AFPS includes one tile.afti_single_tile_per_tile_group_flag equal to 0 specifies that a tilegroup that refers to this AFPS may include more than one tile. When notpresent, the value of afti_single_tile_per_tile_group_flag may beinferred to be equal to 1).

afti_num_tiles_in_atlas_frame_minus1 specifies the number of tiles ineach atlas frame referring to the AFPS.

afti_tile_idx[i] specifies the tile index of the i-th tile in each atlasframe referring to the AFPS).

Based on the value of afti_num_tile_groups_in_atlas_frame_minus1,afti_tile_idx[i] is included in the atlas frame tile information.

When afti_single_tile_per_tile_group_flag is equal to 0,afti_num_tile_groups_in_atlas_frame_minus1 is carried in the atlas frametile information.

afti_num_tile_groups_in_atlas_frame_minus1 plus 1 specifies the numberof tile groups in each atlas frame referring to the AFPS. The value ofafti_num_tile_groups_in_atlas_frame_minus1 may be in the range of 0 toNumTilesInAtlasFrame−1, inclusive. When not present andafti_single_tile_per_tile_group_flag is equal to 1, the value ofafti_num_tile_groups_in_atlas_frame_minus1 may be inferred to be equalto NumTilesInAtlasFrame−1.

The following elements are included in the atlas frame tile informationaccording to the value of as much asafti_num_tile_groups_in_atlas_frame_minus1.

afti_top_left_tile_idx[i] specifies the tile index of the tile locatedat the top-left corner of the i-th tile group (tile). The value ofafti_top_left_tile_idx[i] is not equal to the value ofafti_top_left_tile_idx[j] for any i not equal to j. When not present,the value of afti_top_left_tile_idx[i] may be inferred to be equal to i.The length of the afti_top_left_tile_idx[i] syntax element may beCeil(Log2(NumTileslnAtlasFrame) bits.

afti_bottom_right_tile_idx_delta[i] specifies the difference between thetile index of the tile located at the bottom-right corner of the i-thtile group (tile) and afti_top_left_tile_idx[i]. Whenafti_single_tile_per_tile_group_flag is equal to 1, the value ofafti_bottom_right_tile_idx_delta[i] is inferred to be equal to 0. Thelength of the afti_bottom_right_tile_idx_delta[i] syntax element isCeil(Log2(NumTilesInAtlasFrame−afti_top_left_tile_idx[i])) bits.

afti_signalled_tile_group_id_flag equal to 1 specifies that the tilegroup ID for each tile group is signaled.

When afti_signalled_tile_group_id_flag is equal to 1,afti_signalled_tile_group_id_length_minus1 and afti_tile_group id[i] maybe carried in the atlas frame tile information. When the value of thisflag is 0, tile group IDs may not be signaled.

afti_signalled_tile_group_id_length_minus1 plus 1 specifies the numberof bits used to represent the syntax element afti_tile_group_id[i] whenpresent, and the syntax element atgh_address in tile group headers.

afti_tile_group_id[i] specifies the tile group ID of the i-th tilegroup. The length of the afti_tile_group_id[i] syntax element isafti_signalled_tile_group_id_length_minus1+1 bits.

afti_tile_group_id[i] is included in the atlas frame tile informationaccording to the value of afti_num_tile_groups_in_atlas_frame_minus1.

FIG. 34 shows supplemental enhancement information (SEI) according toembodiments.

FIG. 34 shows the detailed syntax of SEI information contained in abitstream according to embodiments as shown in FIG. 30.

The reception method/device, the system, and the like according to theembodiments may decode, reconstruct, and display point cloud data basedon the SEI message.

The SEI message indicates, based on each payloadType, that the payloadmay contain corresponding data.

For example, when payloadType is equal to 13, the payload may contain 3Dregion mapping information (3d_region_mapping(payloadSize)).

When psd_unit_type is PSD_PREFIX_SEI, the SEI information according tothe embodiments may include buffering_period(payloadSize),pic_timing(payloadSize), filler_payload(payloadSize),user_data_registered_itu_t_t35(payloadSize),user_data_unregistered(payloadSize), recovery_point(payloadSize),no_display(payloadSize), time_code(payloadSize),regional_nesting(payloadSize), sei_manifest(payloadSize),sei_prefix_indication(payloadSize), geometry_transformation_params(payloadSize), 3d_bounding_box_info(payloadSize) (see FIG. 35 and thelike), 3d_region_mapping(payloadSize) (see FIG. 36 and the like), andreserved_sei_message(payloadSize).

When psd_unit_type is PSD_SUFFIX_SEI, the SEI according to theembodiments may include filler_payload(payloadSize),user_data_registered_itu_t_t35(payloadSize),user_data_unregistered(payloadSize), decoded_pcc_hash(payloadSize), andreserved_sei_message(payloadSize).

FIG. 35 shows 3D bounding box SEI according to embodiments.

FIG. 35 shows detailed syntax of SEI information contained in abitstream according to embodiments as shown in FIG. 30.

3dbi_cancel_flag equal to 1 indicates that the 3D bounding boxinformation SEI message cancels the persistence of any previous 3dbounding box information SEI message in output order.

object_id is the identifier of the point cloud object/content carried inthe bitstream.

3d_bounding_box_x indicates the x coordinate value of the originposition of the 3D bounding box of the object.

3d_bounding_box_y indicates the y coordinate value of the originposition of the 3D bounding box of the object.

3d_bounding_box_z indicates the z coordinate value of the originposition of the 3D bounding box of the object.

3d_bounding_box_delta_x indicates the size of the bounding box on the xaxis of the object.

3d_bounding_box_delta_y indicates the size of the bounding box on the yaxis of the object.

3d_bounding_box_delta_z indicates the size of the bounding box on the zaxis of the object.

FIG. 36 shows a 3D region mapping information SEI message according toembodiments.

FIG. 36 shows detailed syntax of SEI information contained in abitstream according to embodiments as shown in FIG. 30.

3dmi_cancel_flag equal to 1 indicates that the 3D region mappinginformation SEI message cancels the persistence of any previous 3Dregion mapping information SEI message in output order.

num_3d_regions may indicate the number of 3D regions signaled in theSEI.

The following elements as many as the value of num_3d_regions may beincluded in this SEI message.

3d_region_idx[i] may indicate the identifier of the i-th 3D region.

3d_region_anchor_x[i], 3d_region_anchor_y[i], and 3d_region_anchor_z[i]may indicate x, y, and z coordinate values of the anchor point of thei-th 3D region, respectively. For example, when the 3D region is of acuboid type, the anchor point may be the origin of the cuboid.

3d_region_anchor_x[i], 3d_region_anchor_y[i], and 3d_region_anchor_z[i]may indicate the x, y, and z coordinate values of the origin position ofthe cuboid of the i-th 3D region.

3d_region_type[i] may indicate the type of the i-th 3D region, and mayhave 0x01-cuboid as a type value.

3d_region_type[i] equal to 1 may indicate that the type of the 3D regionis a cuboid. Hereinafter, elements related to the cuboid type may beincluded in this SEI message.

3d_region_delta_x[i], 3d_region_delta_y[i], and 3d_region_delta_y[i] mayindicate difference values of the i-th 3D region on the x, y, and zaxes.

num_2d regions[i] may indicate the number of 2D regions of a frame inwhich video or atlas data associated with the i-th 3D region is present.

The following elements as many as the value of num_2d_regions[i] may beincluded in this SEI message.

2d_region_idx [j] may indicate the identifier of the j-th 2D region.

2d_region_top [j] and 2d_region_left[j] may include vertical coordinatesand horizontal coordinates within a frame of the top-left position ofthe j-th 2D region, respectively.

2d_region_width [j] and 2d_region_height [j] may include horizontalrange (width) and vertical range (height) values in the frame of thej-th 2D region, respectively.

The 3d region-related fields and 2d region-related fields of the 3dregion mapping information of FIG. 36 may correspond to volumetricrectangle information contained in the bitstream according to theembodiments. Specifically, the bounding box related fields (e.g.,vri_bounding_box_top, vri_bounding_box_left, vri_bounding_box_width, andvri_bounding_box_height) of the volumetric rectangle informationindicate a 2D region. In addition, an object-related field of thevolumetric rectangle information, for example, vri_rectangle_object_idxmay correspond to object_idx contained in scene_object_information. Inother words, object_idx represents 3D region information. This isbecause scene_object_information includes signaling information about a3D bounding box, that is, a 3D region.

The 3d region-related fields and the 2d region-related fields of the 3Dregion mapping information of FIG. 36 may correspond to the tileinformation (tile id, 2D region) and patch object idx of patchinformation contained in the bitstream according to the embodiments,respectively.

num_tiles [j] may indicate the number of atlas tiles or video tilesassociated with the j-th 2D region.

The following tile-related elements as many as the value of num_tiles[j] may be included in this SEI message.

tile_idx [k] may indicate the identifier of an atlas tile or video tileassociated with the k-th 2D region.

num_tile_groups [j] may indicate the number of atlas tile groups orvideo tile groups associated with the j-th 2D region. This value maycorrespond to the number of tiles.

The following element as many as the value of num_tile_groups [j] may beincluded in this SEI message.

tile_group_idx [m] may indicate the identifier of an atlas tile group orvideo tile group associated with the m-th 2D region. This value maycorrespond to the tile index.

Due to the signaling scheme according to the embodiments, the receptionmethod/device according to the embodiments may identify a mappingrelationship between the 3D region and one or more atlas tiles (2Dregions) and acquire corresponding data.

FIG. 37 shows volumetric tiling information according to embodiments.

FIG. 37 shows detailed syntax of SEI information contained in thebitstream according to the embodiments as shown in FIG. 30.

Volumetric tiling information SEI message

This SEI message informs a V-PCC decoder according to the embodimentsavoid different characteristics of a decoded point cloud, includingcorrespondence of areas within a 2D atlas and the 3D space, relationshipand labeling of areas and association with objects.

The persistence scope for this SEI message may be the remainder of thebitstream or until a new volumetric tiling SEI message is encountered.Only the corresponding parameters specified in the SEI message may beupdated. Previously defined parameters from an earlier SEI message maypersist if not modified and if the value of vti_cancel_flag is not equalto 1.

FIG. 38 shows volumetric tiling information objects according toembodiments.

FIG. 38 shows detailed syntax of volumetric tiling info objectsinformation included in FIG. 37.

Based on vtiObjectLabelPresentFlag, vti3dBoundingBoxPresentFlag,vtiObjectPriorityPresentFlag, tiObjectHiddenPresentFlag,vtiObjectCollisionShapePresentFlag, vtiObjectDependencyPresentFlag, andthe like, volumetric_tiling_info_objects may include elements as shownin FIG. 38.

FIG. 39 shows volumetric tiling information labels according toembodiments.

FIG. 39 shows detailed syntax of volumetric_tiling_info_labels includedin FIG. 37.

vti_cancel_flag equal to 1 indicates that the volumetric tilinginformation SEI message cancels the persistence of any previousvolumetric tiling information SEI message in output order.vti_cancel_flag equal to 0 indicates that volumetric tiling informationfollows as shown in FIG. 37.

vti_object_label_present flag equal to 1 indicates that object labelinformation is present in the current volumetric tiling information SEImessage. vti_object_label_present_flag equal to 0 indicates that objectlabel information is not present.

vti_3d_bounding_box_present_flag equal to 1 indicates that 3D boundingbox information is present in the current volumetric tiling informationSEI message. vti_3d_bounding_box_present_flag equal to 0 indicates that3D bounding box information is not present.

vti_object_priority_present flag equal to 1 indicates that objectpriority information is present in the current volumetric tilinginformation SEI message. vti_object_priority_present flag equal to 0indicates that object priority information is not present.

vti_object_hidden_present flag equal to 1 indicates that hidden objectinformation is present in the current volumetric tiling information SEImessage. vti_object_hidden_present_flag equal to 0 indicates that hiddenobject information is not present.

vti_object_collision_shape_present_flag equal to 1 indicates that objectcollision information is present in the current volumetric tilinginformation SEI message. vti_object_collision_shape_present_flag equalto 0 indicates that object collision shape information is not present.

vti_object_dependency_present flag equal to 1 indicates that objectdependency information is present in the current volumetric tilinginformation SEI message. vti_object_dependency_present flag equal to 0indicates that object dependency information is not present.

vti_object_label_language_present flag equal to 1 indicates that objectlabel language information is present in the current volumetric tilinginformation SEI message. vti_object_label_language_present flag equal to0 indicates that object label language information is not present.

vti_bit_equal_to_zero shall be equal to 0.

vti_object_label_language contains a language tag followed by a nulltermination byte equal to 0x00. The length of thevti_object_label_language syntax element may be less than or equal to255 bytes, not including the null termination byte.

vti_num_object_label_updates indicates the number of object labels thatare to be updated by the current SEI.

vti_label_idx[i] indicates the label index of the i-th label to beupdated.

vti_label_cancel_flag equal to 1 indicates that the label with indexequal to vti_label_idx[i] shall be canceled and set equal to an emptystring. vti_label_cancel_flag equal to 0 indicates that the label withindex equal to vti_label_idx[i] shall be updated with information thatfollows this element.

vti_bit_equal_to_zero shall be equal to 0

vti_label[i] indicates the label of the i-th label. The length of thevti_label[i] syntax element may be less than or equal to 255 bytes, notincluding the null termination byte.

vti_bounding_box_scale_log2 indicates the scale to be applied to the 2Dbounding box parameters that may be specified for an object.

vti_3d_bounding_box_scale_log2 indicates the scale to be applied to the3D bounding box parameters that may be specified for an object.

vti_3d_bounding_box_precision_minus8 plus 8 indicates the precision ofthe 3D bounding box parameters that may be specified for an object.

vti_num_object_updates indicates the number of objects that are to beupdated by the current SEI.

Object-related information is included in the volumetric tilinginformation object (see FIG. 38) according to the value ofvti_num_object_update.

vti_object_idx[i] indicates the object index of the i-th object to beupdated.

vti_object_cancel_flag[i] equal to 1 indicates that the object withindex equal to i shall be canceled and that the variableObjectTracked[i] shall be set to 0. Its 2D and 3D bounding boxparameters may be set equal to 0. vti_object_cancel_flag equal to 0indicates that the object with index equal to vti_object_idx[i] shall beupdated with information that follows this element and that the variableObjectTracked[i] shall be set to 1.

vti_bounding_box_update_flag[i] equal to 1 indicates that 2D boundingbox information is present for object with object index i.vti_bounding_box_update_flag[i] equal to 0 indicates that 2D boundingbox information is not present.

When vti_bounding_box_update_flag is equal to 1 for vti_object_idx[i],the following bounding box elements for vti_object_idx[i] are includedin the volumetric tiling information object.

vti_bounding_box top[i] indicates the vertical coordinate value of thetop-left position of the bounding box of an object with index i withinthe current atlas frame.

vti_bounding_box left[i] indicates the horizontal coordinate value ofthe top-left position of the bounding box of an object with index iwithin the current atlas frame.

vti_bounding_box_width[i] indicates the width of the bounding box of anobject with index i.

vti_bounding_box_height[i] indicates the height of the bounding box ofan object with index i.

When vti_3d_bounding_box_update_flag[i] is equal to 1, the followingbounding box elements are included in the volumetric tiling informationobject.

vti_3d_bounding_box_update_flag[i] equal to 1 indicates that 3D boundingbox information is present for object with object index i.vti_3d_bounding_box_update_flag[i] equal to 0 indicates that 3D boundingbox information is not present.

When vti_3d_bounding_box_update_flag is equal to 1 forvti_object_idx[i], the following bounding box related elements areincluded in the volumetric tiling information object.

vti_3d_bounding_box_x[i] indicates the x coordinate value of the originposition of the 3D bounding box of an object with index i.

vti_3d_bounding_box_y[i] indicates they coordinate value of the originposition of the 3D bounding box of an object with index i.

vti_3d_bounding_box_z[i] indicates the z coordinate value of the originposition of the 3D bounding box of an object with index i.

vti_3d_bounding_box_delta_x[i] indicates the size of the bounding box onthe x axis of an object with index i.

vti_3d_bounding_box_delta_y[i] indicates the size of the bounding box onthe y axis of an object with index i.

vti_3d_bounding_box_delta_z[i] indicates the size of the bounding box onthe z axis of an object with index i.

When vtiObjectPriorityPresentFlag is equal to 1, the following priorityrelated elements are included in the volumetric tiling informationobject.

vti_object_priority_update_flag[i] equal to 1 indicates that objectpriority update information is present for an object with index i.vti_object_priority_update_flag[i] equal to 0 indicates that objectpriority information is not present.

vti_object_priority_value[i] indicates the priority of an object withindex i. The lower the priority value, the higher the priority.

When vtiObjectHiddenPresentFlag is equal to 1, the following hiddeninformation for vti_object_idx[i] is included in the volumetric tilinginformation object.

vti_object_hidden_flag[i] equal to 1 indicates that the object withindex i shall be hidden. vti_object_hidden_flag[i] equal to 0 indicatesthat the object with index i shall become present.

When vtiObjectLabelPresentFlag is equal to 1, a label-related updateflag is included in the volumetric tiling information object.

vti_object_label_update_flag equal to 1 indicates that object labelupdate information is present for object with object index i.vti_object_label_update_flag[i] equal to 0 indicates that object labelupdate information is not present.

When vti_object_label_update_flag is equal to 1 for vti_object_idx[i],the object label index for vti_object_idx[i] is included in thevolumetric tiling information object.

vti_object_label_idx[i] indicates the label index of an object withindex i.

When vtiObjectCollisionShapePresentFlag is equal to 1, an objectcollision related element is included in the volumetric tilinginformation object.

vti_object_collision_shape_update_flag[i] equal to 1 indicates thatobject collision shape update information is present for object withobject index i. vti_object_collision_shape_update_flag[i] equal to 0indicates that object collision shape update information is not present.

When vti_object_collision_shape_update_flag is equal to 1 forvti_object_idx[i], vti_object_collision_shape_id[i] forvti_object_idx[i] is included in the volumetric tiling informationobject.

vti_object_collision_shape_id[i] indicates the collision shape ID of anobject with index i.

When vtiObjectDependencyPresentFlag is equal to 1, an object dependencyrelated element is included in the volumetric tiling information object.

vti_object_dependency_update_flag[i] equal to 1 indicates that objectdependency update information is present for object with object index i.vti_object_dependency_update_flag[i] equal to 0 indicates that objectdependency update information is not present.

When vti_object_dependency_update_flag is equal to 1 forvti_object_idx[i], an object dependency related element forvti_object_idx[i] is included in the volumetric tiling informationobject.

vti_object_num_dependencies[i] indicates the number of dependencies ofan object with index i.

Object dependency indexes as many as the value of vti_object_numdependencies are included in the volumetric tiling information object.

vti_object_dependency_idx[i][j] indicates the index of the j-th objectthat has a dependency with the object with index i.

FIG. 40 shows the structure of an encapsulated V-PCC data containeraccording to embodiments.

FIG. 41 shows an encapsulated V-PCC data container structure accordingto embodiments.

The point cloud video encoder 10002 of the transmission device 10000 ofFIG. 1, the encoders of FIGS. 4 and 15, the transmission device of FIG.18, the video/image encoders 20002 and 20003 of FIG. 29, the processorand the encoders 21000 to 21008 of FIG. 21, and the XR device 2330 ofFIG. 23 generate a bitstream containing point cloud data according toembodiments.

The file/segment encapsulator 10003 of FIG. 1, the file/segmentencapsulator 20004 of FIG. 20, the file/segment encapsulator 21009 ofFIG. 21, and the XR device of FIG. 23 format the bitstream in the filestructure of FIGS. 24 and 25.

Similarly, the file/segment decapsulation module 10007 of the receptiondevice 10005 of FIG. 1, the file/segment decapsulators 20005, 21009, and22000 of FIGS. 20 to 23, and the XR device 2330 of FIG. 23 receive anddecapsulate a file and parse the bitstream. The bitstream is decoded bythe point cloud video decoder 10008 of FIG. 1, the decoders of FIGS. 16and 17, the reception device of FIG. 19, the video/image decoders 20006,21007, 21008, 22001, and 22002 of FIGS. 20 to 23, and the XR device 2330of FIG. 23 to restore the point cloud data.

FIGS. 40 and 41 show the structure of a point cloud data containeraccording to the ISOBMFF file format.

FIGS. 40 and 41 show the structure of a container for delivering pointclouds based on multiple tracks.

The methods/devices according to the embodiments may transmit/receive acontainer file containing point cloud data and additional data relatedto the point cloud data based on a plurality of tracks.

Track-1 40000 is an attribute track, and may contain attribute data40040 encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-2 40010 is an occupancy track, and may contain geometry data 40050encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-3 40020 is a geometry track, and may contain occupancy data 40060encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-4 40030 is a v-pcc (v3c) track, and may contain an atlas bitstream40070 containing data related to point cloud data.

Each track is composed of a sample entry and a sample. The sample is aunit corresponding to a frame. In order to decode the N-th frame, asample or sample entry corresponding to the N-th frame is required. Thesample entry may contain information describing the sample.

FIG. 41 is a detailed structural diagram of FIG. 40.

The v3c track 41000 corresponds to track-4 40030. Data contained in thev3c track 41000 may have a format of a data container referred to as abox. The v3c track 41000 contains reference information about the V3Ccomponent tracks 41010 to 41030.

The reception method/device according to the embodiments may receive acontainer (which may be referred to as a file) containing point clouddata as shown in FIG. 41 and parses a V3C track, and may decode andrestore occupancy data, geometry data, and attribute data based on thereference information contained in the V3C track.

The occupancy track 41010 corresponds to track-2 40010 and containsoccupancy data. The geometry track 41020 corresponds to track-3 40020and contains geometry data. The attribute track 41030 corresponds totrack-1 40000 and contains attribute data.

Hereinafter, the syntax of the data structure included in the file ofFIGS. 40 and 41 will be described in detail.

Volumetric Visual Track

Each volumetric visual scene is represented by a unique volumetricvisual track.

An ISOBMFF file may contain multiple scenes, and therefore multiplevolumetric visual tracks may be present in the file.

A volumetric visual track is identified by the volumetric visual mediahandler type ‘vole’ in the HandlerBox of the MediaBox. A volumetricvisual media header is defined as follows.

Volumetric Visual Media Header

Box Type: ‘vvhd’

Container: MediaInformationBox

Mandatory: Yes

Quantity: Exactly one

Volumetric visual tracks shall use a VolumetricVisualMediaHeaderBox inthe MediaInformationBox.

aligned(8) class VolumetricVisualMediaHeaderBox extends FullBox(‘vvhd’,version = 0, 1) { }

‘version’ is an integer that specifies the version of this box

Volumetric Visual Sample Entry

Volumetric visual tracks shall use a VolumetricVisualSampleEntry.

class VolumetricVisualSampleEntry(codingname) extends SampleEntry(codingname){ unsigned int(8)[32] compressor_name; }

compressor_name is a name for informative purposes. It may be formattedin a fixed 32-byte field, with the first byte set to the number of bytesto be displayed, followed by that number of bytes of displayable dataencoded using UTF-8, and then padding to complete 32 bytes total(including the size byte). The field may be set to 0.

Volumetric Visual Samples

The format of a volumetric visual sample is defined by the codingsystem.

V-PCC Unit Header Box

This box may be present in both the V-PCC track (in the sample entry)and in all video-coded V-PCC component tracks (in the schemeinformation). It contains the V-PCC unit header for the data carried bythe respective tracks.

aligned(8) class VPCCUnitHeaderBox extends FullBox(‘vunt’, version = 0,0) { vpcc_unit_header( ) unit_header; }

The box contains a vpcc_unit_header( ) as the above.

V-PCC Decoder Configuration Record

This record contains a version field. This version of the specificationdefines version 1 of this record. Incompatible changes to the recordwill be indicated by a change of version number. Readers are not attemptto decode this record or the streams to which it applies if the versionnumber is unrecognizable.

The array for VPCCParameterSet includes vpcc_parameter_set( ) defined asabove.

The atlas_setupUnit arrays shall include atlas parameter sets that areconstant for the stream referred to by the sample entry in which thedecoder configuration record is present as well as atlas stream SEImessages.

aligned(8) class VPCCDecoderConfigurationRecord { unsigned int(8)configurationVersion = 1; unsigned int(3) sampleStreamSizeMinusOne;unsigned int(5) numOfVPCCParameterSets; for (i=0; i<numOfVPCCParameterSets; i++) { sample_stream_vpcc_unit VPCCParameterSet;}  unsigned int(8) numOfAtlasSetupUnits; for (i=0; i<numOfAtlasSetupUnits; i++) { sample_stream_vpcc_unit atlas_setupUnit; }}

configurationVersion is a version field. Incompatible changes to therecord are indicated by a change of version number.

sampleStreamSizeMinusOne plus 1 indicates the precision, in bytes, ofthe ssvu_vpcc_unit_size element in all sample stream V-PCC units ineither this configuration record or a V-PCC sample in the stream towhich this configuration record applies.

numOfVPCCParameterSets specifies the number of V-PCC parameter sets(VPS) signaled in the decoder configuration record.

VPCCParameterSet is a sample_stream_vpcc_unit( ) instance for a V-PCCunit of type VPCC_VPS. This V-PCC unit includes the vpcc_parameter_set()

numOfAtlasSetupUnits indicates the number of setup arrays for the atlasstream signaled in this configuration record.

Atlas_setupUnit is a sample_stream_vpcc_unit( ) instance containing anatlas sequence parameter set, an atlas frame parameter set, or a SEIatlas NAL unit. For example, reference may be made to the description ofISO/IEC 23090-5.

According to embodiments, VPCCDecoderConfigurationRecord may be definedas follows.

aligned(8) class VPCCDecoderConfigurationRecord { unsigned int(8)configurationVersion = 1; unsigned int(3) sampleStreamSizeMinusOne;bit(2) reserved = 1; unsigned int(3) lengthSizeMinusOne;  unsignedint(5) numOVPCCParameterSets; for (i=0; i< numOVPCCParameterSets; i++) {sample_stream_vpcc_unit VPCCParameterSet; } unsigned int(8)numOfSetupUnitArrays; for (j=0; j<numOfSetupUnitArrays; j++) {  bit(1)array_completeness;  bit(1) reserved = 0;  unsigned int(6)NAL_unit_type;  unsigned int(8) numNALUnits;  for (i=0; i<numNALUnits;i++) { sample_stream_nal_unit setupUnit;  } }

configurationVersion is a version field. Incompatible changes to therecord are indicated by a change of version number.

lengthSizeMinusOne plus 1 indicates the precision, in bytes, of thessnu_nal_unit_size element in all sample stream NAL units in either thisconfiguration record or a V-PCC sample in the stream to which thisconfiguration record applies.

sampleStreamSizeMinusOne plus 1 indicates the precision, in bytes, ofthe ssvu_vpcc_unit_size element in all sample stream V-PCC unitssignaled in this configuration record.

numOfVPCCParameterSets specifies the number of V-PCC parameter sets(VPSs) signaled in this configuration record.

VPCCParameterSet is a sample_stream_vpcc_unit( ) instance for a V-PCCunit of type VPCC_VPS.

numOfSetupUnitArrays indicates the number of arrays of atlas NAL unitsof the indicated types.

array_completeness equal to 1 indicates that all atlas NAL units of thegiven type are in the following array and none are in the stream.array_completeness equal to 0 indicates that additional atlas NAL unitsof the indicated type may be in the stream. The default and permittedvalues are constrained by the sample entry name.

NAL_unit_type indicates the type of the atlas NAL units in the followingarray (which shall be all of that type). It takes a value as defined inISO/IEC 23090-5. It may indicate a NAL_ASPS, NAL_PREFIX_SEI, orNAL_SUFFIX_SEI atlas NAL unit.

numNALUnits indicates the number of atlas NAL units of the indicatedtype included in the configuration record for the stream to which thisconfiguration record applies. The SEI array may only contain SEImessages of a ‘declarative’ nature, that is, those that provideinformation about the stream as a whole. An example of such an SEI maybe a user-data SEI.

setupUnit is a sample_stream_nal_unit( ) instance containing an atlassequence parameter set, an atlas frame parameter set, or a declarativeSEI atlas NAL unit

V-PCC Atlas Parameter Set Sample Group

The ‘vaps’ grouping_type for sample grouping represents the assignmentof samples in V-PCC track to the atlas parameter sets carried in thissample group. When a SampleToGroupBox with grouping_type equal to ‘vaps’is present, a SampleGroupDescriptionBox with the same grouping type ispresent, and contains the ID of this group to which samples belong.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘vaps’.

aligned(8) class VPCCAtlasParamSampleGroupDescriptionEntry( ) extendsSampleGroupDescriptionEntry(‘vaps’) { unsigned int(8)numOfAtlasParameterSets; for (i=0; i<numOfAtlasParameterSets; i++) {sample_stream_vpcc_unit atlasParameterSet; } }

numOfAtlasParameterSets specifies the number of atlas parameter setssignalled in the sample group description.

atlasParameterSet is a sample_stream_vpcc_unit( ) instance containingatlas sequence parameter set, atlas frame parameter set associated withthis group of samples.

The atlas parameter sample group description entry may be configured asfollows.

aligned(8) class VPCCAtlasParamSampleGroupDescriptionEntry( ) extendsSampleGroupDescriptionEntry(‘vaps’) { unsigned int(3)lengthSizeMinusOne; unsigned int(5) numOfAtlasParameterSets; for (i=0;i<numOfAtlasParameterSets; i++) { sample_stream_nal_unitatlasParameterSetNALUnit; } }

lengthSizeMinusOne plus 1 indicates the precision, in bytes, of thessnu_nal_unit_size element in all sample stream NAL units signalled inthis sample group description.

atlasParameterSetNALUnit is a sample_stream_nal_unit( ) instancecontaining atlas sequence parameter set, atlas frame parameter setassociated with this group of samples.

V-PCC SEI Sample Group

The ‘vsei’ grouping_type for sample grouping represents the assignmentof samples in V-PCC track to the SEI information carried in this samplegroup. When a SampleToGroupBox with grouping_type equal to ‘vsei’ ispresent, an accompanying SampleGroupDescriptionBox with the samegrouping type is present, and contains the ID of this group of samplesbelong to.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘vsei’.

aligned(8) class VPCCSEISampleGroupDescriptionEntry( ) extendsSampleGroupDescriptionEntry(‘vsei’) { unsigned int(8) numOfSEIs; for(i=0; i<numOfSEISets; i++) { sample_stream_vpcc_unit sei; } }

numOfSEIs specifies the number of V-PCC SEIs signaled in the samplegroup description.

sei is a sample_stream_vpcc_unit( ) instance containing SEI informationassociated with this group of samples.

The V-PCC SEI sample group description entry may be configured asfollows.

aligned(8) class VPCCSEISampleGroupDescriptionEntry( ) extends

SampleGroupDescriptionEntry(‘vsei’) { unsigned int(3)lengthSizeMinusOne; unsigned int(5) numOfSEIs; for (i=0; i<numOfSEIs;i++) { sample_stream_nal_unit seiNALUnit; } }

lengthSizeMinusOne plus 1 indicates the precision, in bytes, of thessnu_nal_unit_size element in all sample stream NAL units signaled inthis sample group description.

seiNALUnit is a sample_stream_nal_unit( ) instance containing SEIinformation associated with this group of samples.

V-PCC Bounding Box Sample Group

The ‘vpbb’ grouping_type for sample grouping represents the assignmentof samples in V-PCC track to the 3D bounding_box information carried inthis sample group. When a SampleToGroupBox with grouping_type equal to‘vpbb’ is present, an accompanying SampleGroupDescriptionBox with thesame grouping type is present, and contains the ID of this group towhich samples belong.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘vpbb’.

aligned(8) class VPCC3DBoundingBoxSampleGroupDescriptionEntry( ) extendsSampleGroupDescriptionEntry(‘vpbb’) { 3DBoundingBoxInfoStruct( ); }

V-PCC 3D Region Mapping Sample Group

The ‘vpsr’ grouping_type for sample grouping represents the assignmentof samples in V-PCC track to the 3D region mapping information carriedin this sample group. When a SampleToGroupBox with grouping_type equalto ‘vpsr’ is present, an accompanying SampleGroupDescriptionBox with thesame grouping type is present, and contains the ID of this group ofsamples belong to.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘vpsr’.

aligned(8) class VPCC3DRegionMappingSampleGroupDescriptionEntry( )extends SampleGroupDescriptionEntry(‘vpsr’) { VPCC3DRegionMappingBox3d_region_mapping; }

3D Region Track Grouping

TrackGroupTypeBox with track_group_type equal to ‘3drg’ indicates thatthis track belongs to a group of V-PCC component tracks 41010 to 41030that correspond to a 3D spatial region.

Tracks belonging to the same 3D spatial region have the same value oftrack_group_id for track_group_type ‘3drg’. The track_group_id of tracksfrom one 3D spatial region differs from the track_group_id of tracksfrom any other 3D spatial region.

aligned(8) class SpatialRegionGroupBox extends TrackGroupTypeBox(‘3drg’){ }

Tracks that have the same value of track_group_id withinTrackGroupTypeBox with track_group_type equal to ‘3drg’ belong to thesame 3D spatial region.

The track_group_id within TrackGroupTypeBox with track_group_type equalto ‘3drg’ is used as the identifier of the 3D spatial region.

Based on 3D region track grouping according to the embodiments, themethod/device according to the embodiments may provide track groupingincluding data associated with the 3D region of point cloud data. Thereception method/device according to the embodiments may efficientlyacquire and render the point cloud data related to the 3D region.

2D Region Track Grouping

TrackGroupTypeBox with track_group_type equal to ‘2drg’ indicates thatthis track belongs to a group of V-PCC component tracks that correspondto a 2D region.

Tracks belonging to the same 2D region have the same value oftrack_group_id for track_group_type ‘3drg’. The track_group_id of tracksfrom one 2D region differs from the track_group_id of tracks from anyother 2D region.

aligned(8) class SpatialRegionGroupBox extends TrackGroupTypeBox(‘3drg’){ }

Tracks that have the same value of track_group_id withinTrackGroupTypeBox with track_group_type equal to ‘2drg’ belong to thesame 2D region. The track_group_id within TrackGroupTypeBox withtrack_group_type equal to ‘2drg’ is used as the identifier of the 2Dregion.

Based on 2D region track grouping according to the embodiments, themethod/device according to the embodiments may provide track groupingincluding data associated with the 2D region. The receptionmethod/device according to the embodiments may efficiently acquire datarelated to the 2D region and render the point cloud data related to the2D region.

The method/device for receiving point cloud data according toembodiments performs the following operations based on 3D region trackgrouping and/or 2D region track grouping. For example, the receptionmethod/device according to the embodiments may access a 3D bounding_boxbased on the 3D region track grouping, and may access an atlas_tilebased on the 2D region track grouping. In addition, in order to make apartial access to a 3D bounding_box, geometry, attributes, and occupancydata related to the 3D bounding_box should be decoded. In order todecode the V3C components, the relevant information is eventually usedin the atlas bitstream. Accordingly, both the 3D region track groupingand/or the 2D region track grouping may be decoded together by the PCCreceiver.

Multi Track Container of V-PCC Bitstream

The general layout of a multi-track ISOBMFF V-PCC container, where V-PCCunits in a V-PCC elementary stream are mapped to individual trackswithin the container file based on their types. There are two types oftracks in a multi-track ISOBMFF V-PCC container: V-PCC track and V-PCCcomponent track.

The V-PCC track (or v3c track) 40030 or 41000 is a track carrying thevolumetric visual information in the V-PCC bitstream, which includes theatlas sub-bitstream and the sequence parameter sets.

V-PCC component tracks are restricted video scheme tracks which carry 2Dvideo encoded data for the occupancy map, geometry, and attributesub-bitstreams of the V-PCC bitstream. In addition, the followingconditions are satisfied for V-PCC component tracks:

a) in the sample entry, a new box may be inserted which documents therole of the video stream contained in this track, in the V-PCC system;

b) a track reference may be introduced from the V-PCC track, to theV-PCC component track, to establish the membership of the V-PCCcomponent track in the specific point-cloud represented by the V-PCCtrack;

c) the track-header flags may be set to 0, to indicate that this trackdoes not contribute directly to the overall layup of the movie butcontributes to the V-PCC system.

The atlas bitstream describing point cloud data according toembodiments, and signaling information (which may be referred to asparameters, metadata, etc.) may be included in a data structure called abox. The method/device according to the embodiments may include andtransmit the atlas bitstream and parameter information in a v-pcc track(or V3C track) based on multiple tracks. Further, the method/deviceaccording to the embodiments may transmit the atlas bitstream andparameter information according to the embodiments in a sample entry ofthe v-pcc track (or V3C track).

In addition, the method/device according to the embodiments may transmitthe atlas bitstream and parameter information according to theembodiments in a V-PCC elementary stream track on the basis of a singletrack. Furthermore, the method/device according to the embodiments maytransmit the atlas bitstream and parameter information in a sample entryor sample of a V-PCC elementary stream track.

Tracks belonging to the same V-PCC sequence may be time-aligned. Samplesthat contribute to the same point cloud frame across the differentvideo-encoded V-PCC component tracks and the V-PCC track has the samepresentation time. The V-PCC atlas sequence parameter sets and atlasframe parameter sets used for such samples have a decoding time equal orprior to the composition time of the point cloud frame. In addition, alltracks belonging to the same V-PCC sequence have the same implied orexplicit edit lists.

Note: Synchronization between the elementary streams in the componenttracks may be handled by the ISOBMFF track timing structures (stts,ctts, and cslg), or equivalent mechanisms in movie fragments.

Based on this layout, a V-PCC ISOBMFF container shall include thefollowing (see FIG. 40):

-   -   A V-PCC track which contains V-PCC parameter sets (in the sample        entry) and samples carrying the payloads of the V-PCC parameter        set V-PCC unit (of unit type VPCC_VPS) and atlas V-PCC units (of        unit type VPCC AD). This track also includes track references to        other tracks carrying the payloads of video compressed V-PCC        units (i.e., unit types VPCC_OVD, VPCC_GVD, and VPCC_AVD).    -   A restricted video scheme track where the samples contain access        units of a video-coded elementary stream for occupancy map data        (i.e., payloads of V-PCC units of type VPCC_OVD).    -   One or more restricted video scheme tracks where the samples        contain access units of video-coded elementary streams for        geometry data (i.e., payloads of V-PCC units of type VPCC_GVD).    -   Zero or more restricted video scheme tracks where the samples        contain access units of video-coded elementary streams for        attribute data, i.e., payloads of V-PCC units of type VPCC_AVD.

V-PCC tracks

V-PCC Track Sample Entry

Sample Entry Type: ‘vpc1’, ‘vpcg’

Container: SampleDescriptionBox

Mandatory: A ‘vpc1’ or ‘vpcg’ sample entry is mandatory

Quantity: One or more sample entries may be present

V-PCC tracks use VPCCSampleEntry which extendsVolumetricVisualSampleEntry. The sample entry type is ‘vpc1’ or ‘vpcg’.

A VPCC sample entry contains a VPCCConfigurationBox. This box includes aVPCCDecoderConfigurationRecord,

Under the ‘vpc1’ sample entry, all atlas sequence parameter sets, atlasframe parameter sets, or V-PCC SEIs are in the setupUnit array.

Under the ‘vpcg’ sample entry, the atlas sequence parameter sets, atlasframe parameter sets, and V-PCC SEIs may be present in this array, or inthe stream.

An optional BitRateBox may be present in the VPCC volumetric sampleentry to signal the bit rate information of the V-PCC track.

Volumetric Sequences:

class VPCCConfigurationBox extends Box(‘vpcC’) { VPCCDecoderConfigurationRecord( ) VPCCConfig; } aligned(8) classVPCCSampleEntry( ) extends VolumetricVisualSampleEntry (‘vpc1’) {VPCCConfigurationBox config; VPCCUnitHeaderBox unit_header;VPCCBoundingInformationBox ( ); }

A method for transmitting point cloud data according to embodiments mayinclude encoding point cloud data, encapsulating the point cloud data,and transmitting the point cloud data.

According to embodiments, the encapsulating of the point cloud data mayinclude generating one or more tracks containing the point cloud data.

According to embodiments, the one or more tracks may contain point clouddata, for example, attribute data, occupancy data, geometry data, and/orparameters (metadata or signaling information) related thereto.Specifically, a track may include a sample entry describing a sampleand/or the sample. The plurality of tracks may be referred to as a firsttrack, a second track, and the like.

According to embodiments, the point cloud data transmission method maygroup one or more tracks. According to embodiments, the grouped tracksmay correspond to a 2D region representing the point cloud data. The 2Dregion may be an atlas_tile of an atlas frame.

A point cloud data reception method according to embodiments may receivethe grouped tracks. By parsing the grouped tracks, information about theassociated 2D region may be acquired. Accordingly, based on the grouped2D region information, the method/device for receiving point cloud dataaccording to the embodiments may parse the associated geometry,attributes, and occupancy data through spatial partial access toefficiently provide the data to the user.

Based on the 2D region track grouping according to the embodiments, theone or more tracks according to the embodiments may include a trackgroup type box indicating the grouped tracks. The grouped tracks mayhave the same track group ID.

Furthermore, with regard to 2D region track grouping according to theembodiments, track grouping related information according to embodimentsmay include atlas_id, num_tiles, and tile_id for each value ofnum_tiles.

atlas_id is an identifier for an atlas to which the atlas_tile(s)represented by the track group belongs.

num_tiles indicates the number of V3C tiles associated with the trackgroup.

tile_id is an identifier for a V3C tile. This value may be equal to theatlas_tile_group header address (atgh_address).

A point cloud data reception device according to embodiments may includea receiver configured to receive point cloud data, a decapsulatorconfigured to parse the point cloud data, and a decoder configured todecode the point cloud data.

The decapsulator according to embodiments may parse one or more trackscontaining point cloud data.

FIG. 42 shows a V-PCC sample entry according to embodiments.

FIG. 42 shows a structural diagram of sample entries included in theV-PCC track (or V3C track) 40030 of FIG. 40 and the V3C track 41000 ofFIG. 41.

FIG. 42 shows an exemplary V-PCC sample entry structure according to theembodiments of the present disclosure. A sample entry may contain aV-PCC parameter set (VPS) 42000, and optionally contain an atlassequence parameter set (ASPS) 42010, an atlas frame parameter set (AFPS)42020, and/or SEI 42030.

The method/device according to the embodiments may store point clouddata in tracks in a file. Furthermore, parameters (or signalinginformation) related to the point cloud data may be stored andtransmitted/received in a sample or sample entry of a track.

The V-PCC bitstream of FIG. 42 may be generated and parsed byembodiments of generating and parsing of the V-PCC bitstream of FIG. 25.

The V-PCC bitstream may contain a sample stream V-PCC header, a samplestream header, a V-PCC unit header box, and a sample stream V-PCC unit.

The V-PCC bitstream corresponds to the V-PCC bitstream described withreference to FIGS. 25 and 26 or is an example of an extended formthereof.

V-PCC Track Sample Format

Each sample in the V-PCC track corresponds to a single point cloudframe. Samples corresponding to this frame in the various componenttracks shall have the same composition time as the V-PCC track sample.Each V-PCC sample may include one or more atlas NAL units.

aligned(8) class VPCCSample {  unsigned int PointCloudPictureLength =sample_size; // Represents the sample size from SampleSizeBox.  for(i=0; i<PointCloudPictureLength; ) { sample_stream_nal_unit nalUnit i +=(VPCCDecoderConfigurationRecord.lengthSizeMinusOne+1) + nalUnit.ssnu_nal_unit_size;  } } aligned(8) class VPCCSample { unsignedint PictureLength = sample_size; // Represents the sample size fromSampleSizeBox. for (i=0; i<PictureLength; ) // Signaled up to the end ofthe picture. { unsignedint((VPCCDecoderConfigurationRecord.LengthSizeMinusOne+1)*8)NALUnitLength; bit(NALUnitLength * 8) NALUnit; i +=(VPCCDecoderConfigurationRecord.LengthSizeMinusOne+1) + NALUnitLength; }}

VPCCDecoderConfigurationRecord indicates the decoder configurationrecord in the matching V-PCC sample entry.

nalUnit contains a single atlas NAL unit in sample stream NAL unitformat.

NALUnitLength indicates the size of a subsequent NAL unit in bytes.

NALUnit contains a single atlas NAL unit.

V-PCC Track Sync Sample:

A sync sample (random access point) in a V-PCC track is a V-PCC IRAPcoded patch data access unit. Atlas parameter sets may be repeated at async sample for random access, if needed.

Video-Encoded V-PCC Component Tracks

The carriage of coded video tracks that use MPEG-specified codecs arewell defined in ISOBMFF derived specifications. For example, forcarriage of AVC and HEVC coded videos, reference may be made to theISO/IEC 14496-15. ISOBMFF may provide an extension mechanism if othercodec types are required.

Since it is not meaningful to display the decoded frames from attribute,geometry, or occupancy map tracks without reconstructing the point cloudat the player side, a restricted video scheme type may be defined forthese video-coded tracks.

Restricted Video Scheme

V-PCC component video tracks may be represented in the file asrestricted video, and identified by ‘pccv’ in the scheme type field ofthe SchemeTypeBox of the RestrictedSchemeInfoBox of their restrictedvideo sample entries.

It should be noted that there is no restriction on the video codec usedfor encoding the attribute, geometry, and occupancy map V-PCCcomponents. Moreover, these components may be encoded using differentvideo codecs.

Scheme Information

SchemeInformationBox may be present and contain a VPCCUnitHeaderBox.

Referencing V-PCC Component Tracks

To link a V-PCC track to component video tracks, threeTrackReferenceTypeBoxes may be added to a TrackReferenceBox within theTrackBox of the V-PCC track, one for each component. TheTrackReferenceTypeBox contains an array of track IDs designating thevideo tracks which the V-PCC track references. The reference type of aTrackReferenceTypeBox identifies the type of the component such asoccupancy map, geometry, or attribute, or occupancy map. The trackreference types are:

‘pcco’: the referenced track(s) contain the video-coded occupancy mapV-PCC component;

‘pccg’: the referenced track(s) contain the video-coded geometry V-PCCcomponent;

‘pcca’: the referenced track(s) contain the video-coded attribute V-PCCcomponent.

The type of the V-PCC component carried by the referenced restrictedvideo track, and signaled in the RestrictedSchemelnfoBox of the track,shall match the reference type of the track reference from the V-PCCtrack.

FIG. 43 shows track replacement and grouping according to embodiments.

FIG. 43 shows an example in which replacement or grouping of tracks ofan ISOBMFF file structure is applied.

Track Alternatives and Track Grouping:

V-PCC component tracks which have the same alternate_group value aredifferent encoded versions of the same V-PCC component. A volumetricvisual scene may be coded in alternatives. In such a case, all V-PCCtracks which are alternatives of each other have the samealternate_group value in their TrackHeaderBox.

Similarly, when a 2D video track representing one of the V-PCCcomponents is encoded with alternatives, there may be a track referenceto exactly one of those alternatives, and the alternatives form analternate group.

FIG. 43 shows V-PCC component tracks constituting V-PCC content based ona file structure. When the same atlas group ID is given, there are caseswhere the ID is 10, 11, or 12. Tracks 2 and 5, which are attributevideos, may be used interchangeably with each other. Tracks 3 and 6,which are geometry videos, may be replaced with each other. Tracks 4 and7, which are occupancy videos, may be replaced with each other.

Single Track Container of V-PCC Bitstream:

A single-track encapsulation of V-PCC data requires the V-PCC encodedelementary bitstream to be represented by a single-track declaration.

Single-track encapsulation of PCC data may be utilized in the case ofsimple ISOBMFF encapsulation of a V-PCC encoded bitstream. Such abitstream may be directly stored as a single track without furtherprocessing. V-PCC unit header data structures can be kept in thebitstream as-is. A single track container for V-PCC data may be providedto media workflows for further processing (e.g., multi-track filegeneration, transcoding, DASH segmentation, etc.).

An ISOBMFF file which contains single-track encapsulated V-PCC datacontains ‘pest’ in the compatible brands[ ] list of its FileTypeBox.

V-PCC Elementary Stream Track:

Sample Entry Type: ‘vpel’, ‘vpeg’

Container: SampleDescriptionBox

Mandatory: A ‘vpel’ or ‘vpeg’ sample entry is mandatory

Quantity: One or more sample entries may be present

V-PCC elementary stream tracks use VolumetricVisualSampleEntry with asample entry type of ‘vpel’ or ‘vpeg’.

A VPCC elementary stream sample entry contains a VPCCConfigurationBox.

Under the ‘vpe1’ sample entry, all atlas sequence parameter sets, atlasframe parameter sets, and SEIs may be in the setupUnit array. Under the‘vpeg’ sample entry, atlas sequence parameter sets, atlas frameparameter sets, and SEIs may be present in this array or in the stream.

Volumetric Sequences:

class VPCCConfigurationBox extends Box(‘vpcC’) {VPCCDecoderConfigurationRecord( ) VPCCConfig; } aligned(8) classVPCCElementaryStreamSampleEntry( ) extends VolumetricVisualSampleEntry(‘vpe1’) { VPCCConfigurationBox config; VPCCBoundingInformationBox3d_bb; }

V-PCC Elementary Stream Sample Format

A V-PCC elementary stream sample may be comprised of one or more V-PCCunits which belong to the same presentation time. Each such sample has aunique presentation time, a size, and a duration. A sample may be a syncsample or decoding-wise dependent on other V-PCC elementary streamsamples.

V-PCC Elementary Stream Sync Sample:

A V-PCC elementary stream sync sample may satisfy all the followingconditions:

-   -   It is independently decodable;    -   None of the samples that come after the sync sample in decoding        order have any decoding dependency on any sample prior to the        sync sample; and    -   All samples that come after the sync sample in decoding order        are successfully decodable.

V-PCC Elementary Stream Sub-Sample:

A V-PCC elementary stream sub-sample is a V-PCC unit which is containedin a V-PCC elementary stream sample.

A V-PCC elementary stream track contains SubSampleInformationBox in itsSampleTableBox, or in the TrackFragmentBox of each of itsMovieFragmentBoxes, which lists the V-PCC elementary stream sub-samples.

The 32-bit unit header of the V-PCC unit which represents the sub-samplemay be copied to the 32-bit codec_specific_parameters field of thesub-sample entry in the SubSampleInformationBox. The V-PCC unit type ofeach sub-sample may be identified by parsing thecodec_specific_parameters field of the sub-sample entry in theSubSamplelnformationBox.

Information described below may be delivered as follows. For example,when point cloud data is static, it may be carried in a sample entry ofa multi-track V3C track or a sample entry of an elementary track of asingle track. When the point cloud data is dynamic, the information maybe carried in a separate timed metadata track.

Partial Access of Point Cloud Data

3D Bounding Box Information Structure

3DBoundingBoxStruct provides 3D bounding_box information of the pointcloud data, including the x, y, z offset of 3D bounding_box and thewidth, height, and depth of 3D bounding box of the point cloud data.

aligned(8) class 3DBoundingBoxInfoStruct( ) { unsigned int(16) bb_x;unsigned int(16) bb_y; unsigned int(16) bb_z; unsigned int(16)bb_delta_x; unsigned int(16) bb_delta_y; unsigned int(16) bb_delta_z; }

bb_x, bb_y, and bb_z specify the x, y, and z coordinate values of theorigin position of 3D bounding_box of point cloud data in the Cartesiancoordinates, respectively.

bb_delta_x, bb_delta_y, and bb_delta_z indicate the extension of the 3Dbounding_box of point cloud data in the Cartesian coordinates along thex, y, and z axes relative to the origin, respectively.

3D Region Information Structure

3DRegionInfoStruct may contain 3D region information about a partialregion of point cloud data.

aligned(8) class 3DRegionInfoStruct(3d_dimension_included_flag) {unsigned int(16) 3d_region_id; unsigned int(16) 3d_anchor_x; unsignedint(16) 3d_anchor_y; unsigned int(16) 3d_anchor_z;if(3d_dimension_included_flag){ unsigned int(8) 3d_region_type;if(3d_region_type == ‘1’) {//cuboid unsigned int(16) 3d_region_delta_x;unsigned int(16) 3d_region_delta_y; unsigned int(16) 3d_region_delta_z;} } }

3d_region_id may indicate the identifier of the 3D region.

3d_region_anchor_x, 3d_region_anchor_y, and 3d_region_anchor_z mayindicate x, y, and z coordinate values of an anchor point of the 3Dregion, respectively. For example, when the 3D region is of a cuboidtype, the anchor point may be the origin of the cuboid, and3d_region_anchor_x, 3d_region_anchor_y, and 3d_region_anchor_z mayindicate the x, y, z coordinate values of the origin position of thecuboid of the 3D region.

3d_region_type may indicate the type of the 3D region and may have0x01-cuboid as a value.

3d_dimension_included_flag may be a flag indicating whether the 3Dregion contains detailed information, for example, 3d_region_type,3d_region_delta_x, 3d_region_delta_y, and 3d_region_delta_z.

3d_region_delta_x, 3d_region_delta_y, and 3d_region_delta_z may indicatethe difference values along the x, y, and z axes when the 3D region_typeis cuboid.

2D Region Information Structure

aligned(8) class 2DRegionInfoStruct(2d_dimension_included_flag) {unsigned int(8) 2d_region_type; unsigned int(16) 2d_region_id;if(2d_dimension_included_flag){ unsigned int(16) 2d_region_top; unsignedint(16) 2d_region_left; unsigned int(16) 2d_region_width; unsignedint(16) 2d_region_height; } }

2d_region_id may indicate the identifier of a 2D region. According toembodiments, it may match a video tile identifier, a tile_groupidentifier, or an atlas_tile identifier or tile_group identifier in anatlas frame.

2d_region_type may indicate a type representing a 2D region. This mayspecify the shape of a region, i.e., whether the shape is a square, orwhether the 2D region represents a video tile or tile_group, or whetheran atlas_tile or tile_group identifier in an atlas frame is indicated.

2d_region_top and 2d_region_left may include a vertical coordinate valueand a horizontal coordinate value of the top-left position of the 2Dregion within the frame, respectively.

2d_dimension_included_flag may be a flag indicating whether the widthand height values of the 2D region are included.

2d_region_width and 2d_region_height may include the horizontal range(width) and vertical range (height) of the 2D region within the frame,respectively.

FIG. 44 shows a structure of a 3D region mapping information accordingto embodiments.

FIG. 45 shows a structure of a 3D region mapping information accordingto embodiments.

The information in FIGS. 44 and 45 may be delivered as follows. Forexample, when point cloud data is static, it may be carried in a sampleentry of a multi-track V3C track or a sample entry of an elementarytrack of a single track. When the point cloud data is dynamic, theinformation may be carried in a separate timed metadata track.

V-PCC 3D Region Mapping Information Structure

The V-PCC 3D region mapping information structure(VPCC3DRegionMappingInfoStruct) may contain 2D region information aboutone or more geometry, occupancy, or attribute videos or atlas framescontaining data associated with a 3D region of the point cloud datawithin the video or atlas frame. It may also contain an identifier of atrack group including 3D region data (which may refer to a set of tracksincluding data of the same 3D region).

aligned(8) class VPCC3DRegionMappingInfoStruct( ){  unsigned int(16)num_3d_regions;  for (i = 0; i < num_3d_regions; i++) {3DRegionInfoStruct(1);  unsigned int(8) num_2d_regions[i];  for (j=0; j<num_2d_regions[i]; j++){ 2DRegionInfoStruct(1);  } unsigned int(8)num_track_groups[i];  for (k=0 ; k <num_track_groups[i]; k++) unsignedint(32) track_group_id;  } }

3DRegionInfoStruct( ) may represent 3D region information in a 3D spaceof some or all of the point cloud data.

num_2d_regions[i] may indicate the number of 2D regions of one or morevideos or atlas frames containing data related to the point cloud datain the 3D region

2DRegionInfoStruct may indicate 2D region information about geometry,occupancy, or attribute videos or atlas frames containing dataassociated with data related to the point cloud data in the 3D region.

num_track_groups indicates the number of track groups associated with a3D spatial region.

track_group_id identifies the track group for the tracks which carry theV-PCC components for the associated 3D spatial region.

The 3D region mapping information of FIG. 44 may be included in the 3Dregion mapping box of FIG. 45.

V-PCC 3D Region Mapping Information Box

The VPCC 3D region mapping box (VPCC3DRegionMappingBox) may contain thefollowing information: 3D region information in a 3D space of a part orall of the point cloud data, an identifier of a track group includingthe corresponding 3D region data (which may refer to a set of tracksincluding data of the same 3D region), 2D region information about oneor more videos or atlas frames containing data associated with the pointcloud data in the 3D region, information about a video, an atlas_tile,or a tile_group associated with each 2D region, and an identifier of atrack group including 2D region data (which may refer to a set of tracksincluding data of the same 2D region).

aligned(8) class VPCC3DRegionMappingBox extends FullBox(‘vpsr’,0,0) {VPCC3DRegionMappingInfoStruct( ); unsigned int(8) num_2d_regions; for(j=0; j< num_2d_regions; j++) { unsigned int(8) 2d_region_id; unsignedint(8) num_tiles[j]; for (k=0 ; k <num_tiles[j]; k++)  unsignedint(32) tile_id[k]; unsigned int(8) num_tile_groups[j]; for (k=0 ; k<num_groups[j]; k++)  unsigned int(32) tile_group_id[m]; unsigned int(8)num_track_groups[j]; for (k=0 ; k <num_track_groups[j]; k++)  unsignedint(32) track_group_id; } }

2d_region_id is the identifier of the 2D region of the geometry,occupancy, attribute video or atlas frame.

num_tiles is the number of tiles of a video frame or tiles of an atlasframe associated with the 2D region of a geometry, occupancy, attributevideo or atlas frame.

tile_id[k] is a tile identifier of a video frame or an atlas frameassociated with the 2D region of the geometry, occupancy, attributevideo or atlas frame.

num_tile_groups indicates the number of tile groups of a video frame ortile groups of a video frame associated with the 2D region of ageometry, occupancy, attribute video or atlas frame.

tile_group_id is a tile_group identifier of an atlas frame or a videoframe associated with the 2D region of a geometry, occupancy, attributevideo or atlas frame.

num_track_groups indicates the number of track groups associated with a2D region.

track_group_id identifies the track group for the tracks which carry theV-PCC components for the associated 2D region.

Static V-PCC 3D Region Mapping Information

If the 2D region information about one or more video or atlas framescontaining data associated with the 3D region of point cloud data, andinformation about the video or atlas_tile or tile_group associated witheach 2D region do not change within the point cloud sequence,VPCC3DRegionMappingBox may be contained in the sample entry of the V-PCCtrack or V-PCC elementary stream track.

aligned(8) class VPCCSampleEntry( ) extends VolumetricVisualSampleEntry(‘vpc1’) { VPCCConfigurationBox config; VPCCUnitHeaderBox unit_header;VPCC3DRegionMappingBox 3d_region_mapping; }

The 2D region information about an atlas frame signaled in theVPCC3DRegionMappingBox may be 2D region information about the atlasframe included in a sample in the V-PCC track.

The 2D region information about the video (geometry, attribute,occupancy) frame signaled in VPCC3DRegionMappingBox may be 2D regioninformation about the video frame included in the sample in the videotrack (geometry, attribute, occupancy) referenced through the trackreference of the V-PCC track.

   aligned(8) class VPCCElementaryStreamSampleEntry( ) extendsVolumetricVisualSampleEntry (‘vpe1’) {    VPCCConfigurationBox config;  VPCC3DRegionMappingBox 3d_region_mapping;  }

The 2D region information about the video (geometry, attribute,occupancy) frame signaled in the VPCC3DRegionMappingBox may be the 2Dregion information about the video or atlas frame included in asub-sample in the V-PCC elementary stream track.

Dynamic V-PCC 3D Region Mapping Information

If the V-PCC track has an associated timed-metadata track with a sampleentry type ‘dysr’, 3D spatial regions defined for the point cloud streamis carried by the V-PCC track and considered as dynamic regions. Thatis, the spatial region information may dynamically change over time.

The associated timed-metadata track contains a ‘cdsc’ track reference tothe V-PCC track carrying the atlas stream.

The 2D region information about the atlas frame signaled in theVPCC3DRegionMappingBox may be 2D region information about the atlasframe included in a sample in the V-PCC track.

The 2D region information about the video (geometry, attribute,occupancy) frame signaled in the VPCC3DRegionMappingBox may be 2D regioninformation about the video frame included in the sample in the videotrack (geometry, attribute, occupancy) referenced through the trackreference of the V-PCC track.

If the V-PCC elementary stream track has an associated timed-metadatatrack with a sample entry type ‘dysr’, 3D spatial regions defined forthe point cloud stream is carried by the V-PCC elementary track andconsidered as dynamic regions. That is, the spatial region informationmay dynamically change over time.

The associated timed-metadata track contains a ‘cdsc’ track reference tothe V-PCC elementary stream track.

The 2D region information about the video (geometry, attribute,occupancy) frame or atlas frame signaled in the VPCC3DRegionMappingBoxmay be 2D region information about a video or atlas frame contained in asub-sample in a V-PCC elementary stream track.

aligned(8) class Dynamic3DSpatialRegionSampleEntry extendsMetaDataSampleEntry(‘dysr’) { VPCC3DRegionMappingBoxinit_3d_region_mapping; }

The init_3d_region_mapping may include matching information about theinitial 3D region when matching information about a 3D region changesover time.

The sample syntax of this sample entry type ‘dysr’ is specified asfollows:

aligned(8) DynamicSpatialRegionSample( ) { VPCC3DRegionMappingBox3d_region_mapping; }

Point Cloud Bounding Box

VPCCBoundingInformationBox may be present in the sample entry of eitherthe V-PCC track or V-PCC elementary stream track. When it is present inthe sample entry of either the V-PCC track or V-PCC elementary streamtrack, VPCCBoundingInformationBox provides the overall bounding_boxinformation of associated or carried point cloud data.

aligned(8) class VPCCBoundinglnformationBox extends FullBox(‘vpbb’,0,0){ 3DBoundingBoxInfoStruct( ); }

If the V-PCC track has an associated timed-metadata track with a sampleentry type ‘dybb’, the timed metadata track provides dynamically changed3D bounding_box information of point cloud data.

The associated timed-metadata track contains a ‘cdsc’ track reference tothe V-PCC track carrying the atlas stream.

aligned(8) class Dynamic3DBoundingBoxSampleEntry

extends MetaDataSampleEntry(‘dybb’) { VPCCBoundingInformationBox all_bb;}

all_bb provides the overall 3D bounding_box information, including x, y,and z coordinates of the origin position and the extension of theoverall 3D bounding_box of point cloud data in the Cartesian coordinatesalong the x, y, and z axes relative to the origin, respectively. 3Dbounding_box carried in samples in this track is the spatial part ofthis overall 3D bounding_box.

The sample syntax of this sample entry type ‘dybb’ is specified asfollows:

aligned(8) Dynamic3DBoundingBoxSample( ) { VPCCBoundingInformationBox3dBB; }

3dBB provides 3D bounding_box information signaled in the sample.

Regarding the semantics of 3DSpatialRegionStruct,dimensions_included_flag equal to 0 indicates that the dimensions arenot signaled and that they have been previously signaled for the sameregion. That is, a previous instance of a 3DSpatialRegionStruct with thesame 3d_region_id signals the dimensions.

The point cloud data transmission method according to the embodimentsmay generate one or more tracks including 3D region information(PCC3DRegionMappingInfoStruct) for the point cloud data.

According to embodiments, the 3D region information may includeinformation (num_track_groups) indicating the number of track groupsassociated with a 3D region and information (track_group_id) identifyingthe track group for the tracks which carry the point cloud dataassociated with the 3D region.

Accordingly, the point cloud data transmission method/device accordingto the embodiments may generate and transmit a data track groupassociated with a 3D region. Accordingly, the point cloud data receptionmethod/device according to the embodiments may make an efficient spatialaccess to the 3D region based on the data track group associated withthe 3D region according to the embodiments.

The point cloud data transmission method according to the embodimentsmay generate one or more tracks containing 3D region mapping information(VPCC3DRegionMappingBox extends FullBox).

According to embodiments, the 3D region mapping information may includeinformation (num_track_groups) indicating the number of track groupsassociated with the 2D region for point cloud data, and information(track_group_id) identifying the track group for the tracks that carrythe point cloud data associated with the 2D region.

FIG. 46 shows a structure for encapsulating non-timed V-PCC dataaccording to embodiments.

The point cloud data transmission/reception method/device according tothe embodiments and the system included in the transmission/receptiondevice may encapsulate and transmit/receive non-timed V-PCC data asshown in FIG. 46.

When the point cloud data according to the embodiments is an image, thepoint cloud video encoder 10002 of FIG. 1 (or the encoder of FIG. 4, theencoder of FIG. 15, the transmission device of FIG. 18, the processor20001 of FIG. 20, the image encoder 20003 of FIG. 20, the processor ofFIG. 21, or the image encoder 21008 of FIG. 21) may encode the image,the file/segment encapsulator 10003 (or the file/segment encapsulator20004 of FIG. 20 or the file/segment encapsulator 21009 of FIG. 21) maystore the image and image-related information in a container (item) asshown in FIG. 46, and the transmitter 10004 may transmit the container.

Similarly, the receiver of FIG. 1 receives the container of FIG. 46, andthe file/segment decapsulator 10007 (or the file/segment decapsulator20005 of FIG. 20 or the file/segment decapsulator 22000) parses thecontainer. The point cloud video decoder 10008 of FIG. 1 (or the decoderof FIG. 16, the decoder of FIG. 17, the reception device of FIG. 19, orthe image decoder 20006, or the image decoder 22002) may decode theimage included in the item and provide the decoded image to the user.

According to embodiments, the image may be a still image. Themethod/device according to the embodiments may transmit and receivepoint cloud data about the image. The method/device according to theembodiments may store and transmit/receive the image in an item based onthe data container structure as shown in FIG. 46. Attribute informationabout the image may be stored in an image property or the like.

The non-timed V-PCC data is stored in the file as image items. Two newitem types (V-PCC item and V-PCC unit item) are defined to encapsulatethe non-timed V-PCC data.

The new handler type 4CC code ‘vpcc’ is defined and stored in aHandlerBox of MetaBox to indicate presence of V-PCC items, V-PCC unititems, and other V-PCC-encoded content representation information.

V-PCC Items 46000: A V-PCC item is an item which represents anindependently decodable V-PCC access unit. An item type ‘vpci’ isdefined to identify V-PCC items. V-PCC items store V-PCC unit payload(s)of the atlas sub-bitstream. If PrimaryltemBox exists, item_id in thisbox is set to indicate a V-PCC item.

V-PCC Unit Item 46010: A V-PCC unit item is an item which represents aV-PCC unit data. V-PCC unit items store V-PCC unit payload(s) ofoccupancy, geometry, and attribute video data units. A V-PCC unit itemstores only one V-PCC access unit related data.

An item type for a V-PCC unit item is set depending on the codec used toencode corresponding video data units. A V-PCC unit item is associatedwith corresponding V-PCC unit header item property and codec specificconfiguration item property. V-PCC unit items are marked as hidden itemsbecause it is not meaningful to display independently.

In order to indicate the relationship between a V-PCC item and V-PCCunit items, three below item reference types are used. Item reference isdefined “from” a V-PCC item “to” the related V-PCC unit items.

‘pcco’: the referenced V-PCC unit item(s) contain the occupancy videodata units.

‘pccg’: the referenced V-PCC unit item(s) contain the geometry videodata units.

‘pcca’: the referenced V-PCC unit item(s) contain the attribute videodata units.

V-PCC Configuration Item Property 52020

Box Types: ‘vpcp’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’

Quantity (per item): One or more for a V-PCC item of type ‘vpci’

For the V-PCC configuration item property, the box type is ‘vpcp’ andthe property type is a descriptive item property. The container is anItemPropertyContainerBox. It is mandatory per item for a V-PCC item oftype ‘vpci’. One or more properties per item may be present for a V-PCCitem of type ‘vpci’.

V-PCC parameter sets are stored as descriptive item properties and areassociated with the V-PCC items.

aligned(8) class vpcc_unit_payload_struct ( ) { unsigned int(16)vpcc_unit_payload_size; vpcc_unit_payload( ); }

vpcc_unit_payload_size specifies the size in bytes of thevpcc_unit_paylod( ).

aligned(8) class VPCCConfigurationProperty extends ItemProperty(‘vpcc’){ vpcc_unit_payload_struct( )[ ]; }

vpcc_unit_paylod( ) includes a V-PCC unit of type VPCC_VPS.

V-PCC Unit Header Item Property 46030

Box Types: ‘vunt’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

For the V-PCC unit header item property, the box type is ‘vunt’, theproperty type is a descriptive item property, and the container is anItemPropertyContainerBox. It is Mandatory per item for a V-PCC item oftype ‘vpci’ and for a V-PCC unit item. One property may be present peritem.

V-PCC unit header is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

aligned(8) class VPCCUnitHeaderProperty ( ) extendsItemFullProperty(‘vunt’, version=0, 0) { vpcc_unit_header( ); }

Based on the structure of FIG. 46, the method/device/system according tothe embodiments may deliver non-timed point cloud data.

Carriage of Non-timed Video-based Point Cloud Compression Data

The non-timed V-PCC data is stored in a file as image items. A newhandler type 4CC code ‘vpcc’ is defined and stored in the HandlerBox ofthe MetaBox in order to indicate the presence of V-PCC items, V-PCC unititems and other V-PCC encoded content representation information.

An item according to embodiments represents an image. For example, it isdata that does not move and may refer to a single image.

The method/device according to the embodiments may generate and transmitdata according to the embodiments based on a structure for encapsulatingnon-timed V-PCC data, as shown in FIG. 52.

V-PCC Items

A V-PCC item is an item which represents an independently decodableV-PCC access unit. A new item type 4CC code ‘vpci’ is defined toidentify V-PCC items. V-PCC items store V-PCC unit payload(s) of atlassub-bitstream.

If PrimaryItemBox exists, item_id in this box shall be set to indicate aV-PCC item.

V-PCC Unit Item

A V-PCC unit item is an item which represents a V-PCC unit data.

V-PCC unit items store V-PCC unit payload(s) of occupancy, geometry, andattribute video data units. A V-PCC unit item may contain only one V-PCCaccess unit related data.

An item type 4CC code for a V-PCC unit item is set based on the codecused to encode corresponding video data units. A V-PCC unit item isassociated with corresponding V-PCC unit header item property and codecspecific configuration item property.

V-PCC unit items are marked as hidden items, since it is not meaningfulto display independently.

In order to indicate the relationship between a V-PCC item and V-PCCunits, three new item reference types with 4CC codes ‘pcco’, ‘pccg’ and‘pcca’ are defined. Item reference is defined “from” a V-PCC item “to”the related V-PCC unit items. The 4CC codes of item reference types are:

‘pcco’: the referenced V-PCC unit item(s) containing the occupancy videodata units.

‘pccg’: the referenced V-PCC unit item(s) containing the geometry videodata units.

‘pcca’: the referenced V-PCC unit item(s) containing the attribute videodata units.

V-PCC-Related Item Properties

Descriptive item properties are defined to carry the V-PCC parameter setinformation and V-PCC unit header information, respectively:

V-PCC Configuration Item Property

Box Types: ‘vpcp’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’

Quantity (per item): One or more for a V-PCC item of type ‘vpci’

V-PCC parameter sets are stored as descriptive item properties and areassociated with the V-PCC items.

essential is set to 1 for a ‘vpcp’ item property.

aligned(8) class vpcc_unit_payload_struct ( ) { unsigned int(16)vpcc_unit_payload_size; vpcc_unit_payload( ); } aligned(8) classVPCCConfigurationProperty extends ItemProperty(‘vpcc’) {vpcc_unit_payload_struct( )[ ]; }

vpcc_unit_payload_size specifies the size in bytes of thevpcc_unit_paylod( ).

V-PCC Unit Header Item Property

Box Types: ‘vunt’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

V-PCC unit header is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

essential is set to 1 for a ‘vunt’ item property.

aligned(8) class VPCCUnitHeaderProperty ( ) { extendsItemFullProperty(‘vunt’, version=0, 0) { vpcc_unit_header( ); }

V-PCC 3d Bounding Box Item Property

Box Types: ‘v3dd’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

3D bounding information is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

aligned(8) class VPCC3DBoundingBoxInfoProperty ( ) { extendsItemFullProperty(‘v3dd’, version=0, 0) { 3DBoundingBoxInfoStruct( ); }

V-PCC 3D Region Mapping Information Item Property

Box Types: ‘dysr’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

3D bounding information is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

aligned(8) class VPCC3DRegionMappingBoxInforoperty ( ) { extendsItemFullProperty(‘v3dd’, version=0, 0) { VPCC3DRegionMappingInfoStruct(); }

FIG. 47 illustrates a point cloud data transmission method according toembodiments.

The point cloud data transmission method according to the embodimentsincludes encoding point cloud data (S47000). The encoding operationaccording to the embodiments may include operations such as operation ofthe point cloud video encoder 10002 of FIG. 1, operation of the encoderof FIG. 4, operation of the encoder of FIG. 15, and the data input unitor multiplexer 18007 of the transmission device of FIG. 18, operation ofthe pre-processor 20001 or video/image encoder 20002, 20003 of FIG. 20,operation of the pre-processors 21001 to 21006 or the video/imageencoder 21007, 21008 of FIG. 21, operation of the XR device 2330, thebitstream generation of FIGS. 25 and 26.

The point cloud data transmission method according to the embodimentsmay further include encapsulating the point cloud data (S47010).operations such as file/segment encapsulation (10003, 20004, 21009) ofFIGS. 1, 20, and 21, and generation of a file of FIGS. 24 and 25 (seeFIG. 26 or preceding figures). The encapsulation operation according tothe embodiments may include operations such as operation of thefile/segment encapsulator 10003 of FIG. 1, encapsulation of the encodedpoint cloud data bitstream generated by the transmission device of FIG.18, operation of the file/segment encapsulator 20004 of FIG. 20,operation of the file/segment encapsulator 21009 of FIG. 21, operationof the XR device 2330 of FIG. 23, encapsulation of a bitstream in FIGS.25 and 26, encapsulation of a bitstream into a file in FIGS. 40 and 41,and encapsulation of a bitstream into an item in FIG. 46.

The point cloud data transmission method according to the embodimentsmay further include transmitting the point cloud data (S47020). Thetransmission operation according to the embodiments may includeoperations such as point cloud data transmission by the transmitter10004 of FIG. 1, the transmitter 18008 of FIG. 18, the delivery of FIG.20, the delivery of FIG. 21, the XR device of FIG. 23, and point clouddata transmission in FIGS. 25 to 46.

FIG. 48 illustrates a point cloud data reception method according toembodiments.

The point cloud data reception method according to the embodiments mayinclude receiving point cloud data (S48000). The reception operationaccording to the embodiments may include operations such as operation ofthe receiver 10006 of FIG. 1, operation of the receiver of FIG. 19, thereception according to the delivery of FIG. 20, the reception accordingto the delivery of FIG. 22, and the reception by the XR device 2330 ofFIG. 23, the reception of a bitstream in FIGS. 25 and 26, the receptionof a file in FIGS. 40 and 41, and the reception of an item in FIG. 46.

The reception method according to the embodiments may further includedecapsulating the point cloud data (S48010). The decapsulation operationaccording to the embodiments may include operations such asdecapsulation of a container containing data in the file/segmentdecapsulator 10007 of FIG. 1, the file/segment decapsulator 20005 ofFIG. 20, the file/segment decapsulator 22000 of FIG. 22, the XR device2330 of FIG. 23, and FIGS. 25 and 26, and decapsulation of a file inFIGS. 40 and 41, decapsulation of an item in FIG. 46.

The reception method according to the embodiments may further includedecoding the point cloud data (S48020). The decoding operation accordingto the embodiments may include operations such as operation of the pointcloud video decoder 10008 of FIG. 1, operation of the decoder of FIG.16, operation of the decoder of FIG. 17, decoding of point cloud data inFIG. 19, operation of the video/image decoder 20006 of FIG. 20,operation of the video/image decoder 22001, 22002 of FIG. 22, operationof the XR device 2330 of FIG. 23, and decoding of data in FIGS. 25 to43.

According to the proposed method, a transmitter or receiver configuredto provide a point cloud content service may configure a V-PCC bitstreamand store a file as described above.

Metadata for data processing and rendering in the V-PCC bitstream may betransmitted in a bitstream.

The player or the like may be allowed to perform partial access orspatial access to the point cloud object/content according to the user'sviewport. In other words, the above-described data representation method(see FIGS. 24 to 46) may enable efficient access to and processing of apoint cloud bitstream according to the user's viewport.

The point cloud data transmission device according to the embodimentsmay provide a bounding_box for partial access and/or spatial access topoint cloud content (e.g., V-PCC content) and signaling informationtherefor (see FIGS. 24 to 46). Accordingly, the point cloud datareception device according to the embodiments may be allowed to accessthe point cloud content in various ways in consideration of the playeror user environment.

The point cloud data transmission device according to the embodimentsmay provide 3D region information of V-PCC content for supportingspatial access of V-PCC content according to a user viewport and a 2Dregion related metadata on a video or atlas frame associated therewith(see FIGS. 24 to 46).

The point cloud data transmission device according to the embodimentsmay provide signaling of 3D region information about a point cloud in apoint cloud bitstream and information related to a 2D region on a videoor atlas frame associated therewith (see FIGS. 24 to 46).

In addition, the point cloud data reception device according to theembodiments may efficiently provide users with point cloud content withlow latency considering the user environment, based on storage andsignaling of 3D region information about the point cloud in the file and2D region related information on the video or atlas frame associatedtherewith (see FIGS. 24 to 46).

Further, the point cloud data reception device according to theembodiments may provide various accesses to point cloud content based on3D region information about a point cloud associated with image items ina file and 2D region related information on a video or atlas frameassociated therewith (see FIGS. 24 to 46).

The point cloud data transmission device according to the embodimentsmay efficiently encode and provide track grouping including dataassociated with a 3D region of point cloud data and related signalinginformation (see FIGS. 24 to 46).

Further, the point cloud data receiving device according to theembodiments may efficiently access point cloud contents based on trackgrouping including data associated with a 2D region and relatedsignaling information (see FIGS. 24 to 46).

The embodiments have been described in terms of a method and/or adevice. The description of the method and the description of the devicemay complement each other.

Although embodiments have been described with reference to each of theaccompanying drawings for simplicity, it is possible to design newembodiments by merging the embodiments illustrated in the accompanyingdrawings. If a recording medium readable by a computer, in whichprograms for executing the embodiments mentioned in the foregoingdescription are recorded, is designed by those skilled in the art, itmay also fall within the scope of the appended claims and theirequivalents. The devices and methods may not be limited by theconfigurations and methods of the embodiments described above. Theembodiments described above may be configured by being selectivelycombined with one another entirely or in part to enable variousmodifications. Although preferred embodiments have been described withreference to the drawings, those skilled in the art will appreciate thatvarious modifications and variations may be made in the embodimentswithout departing from the spirit or scope of the disclosure describedin the appended claims. Such modifications are not to be understoodindividually from the technical idea or perspective of the embodiments.

Various elements of the devices of the embodiments may be implemented byhardware, software, firmware, or a combination thereof. Various elementsin the embodiments may be implemented by a single chip, for example, asingle hardware circuit. According to embodiments, the componentsaccording to the embodiments may be implemented as separate chips,respectively. According to embodiments, at least one or more of thecomponents of the device according to the embodiments may include one ormore processors capable of executing one or more programs. The one ormore programs may perform any one or more of the operations/methodsaccording to the embodiments or include instructions for performing thesame. Executable instructions for performing the method/operations ofthe device according to the embodiments may be stored in anon-transitory CRM or other computer program products configured to beexecuted by one or more processors, or may be stored in a transitory CRMor other computer program products configured to be executed by one ormore processors. In addition, the memory according to the embodimentsmay be used as a concept covering not only volatile memories (e.g., RAM)but also nonvolatile memories, flash memories, and PROMs. In addition,it may also be implemented in the form of a carrier wave, such astransmission over the Internet. In addition, the processor-readablerecording medium may be distributed to computer systems connected over anetwork such that the processor-readable code may be stored and executedin a distributed fashion.

In this document, the term “/” and “,” should be interpreted asindicating “and/or.” For instance, the expression “A/B” may mean “Aand/or B.” Further, “A, B” may mean “A and/or B.” Further, “AB/C” maymean “at least one of A, B, and/or C.” “A, B, C” may also mean “at leastone of A, B, and/or C.” Further, in the document, the term “or” shouldbe interpreted as “and/or.” For instance, the expression “A or B” maymean 1) only A, 2) only B, and/or 3) both A and B. In other words, theterm “or” in this document should be interpreted as “additionally oralternatively.”

Terms such as first and second may be used to describe various elementsof the embodiments. However, various components according to theembodiments should not be limited by the above terms. These terms areonly used to distinguish one element from another. For example, a firstuser input signal may be referred to as a second user input signal.Similarly, the second user input signal may be referred to as a firstuser input signal. Use of these terms should be construed as notdeparting from the scope of the various embodiments. The first userinput signal and the second user input signal are both user inputsignals, but do not mean the same user input signal unless contextclearly dictates otherwise.

The terminology used to describe the embodiments is used for the purposeof describing particular embodiments only and is not intended to belimiting of the embodiments. As used in the description of theembodiments and in the claims, the singular forms “a”, “an”, and “the”include plural referents unless the context clearly dictates otherwise.The expression “and/or” is used to include all possible combinations ofterms. The terms such as “includes” or “has” are intended to indicateexistence of figures, numbers, steps, elements, and/or components andshould be understood as not precluding possibility of existence ofadditional existence of figures, numbers, steps, elements, and/orcomponents. As used herein, conditional expressions such as “if” and“when” are not limited to an optional case and are intended to beinterpreted, when a specific condition is satisfied, to perform therelated operation or interpret the related definition according to thespecific condition.

Operations according to the embodiments described in this specificationmay be performed by a transmission/reception device including a memoryand/or a processor according to embodiments. The memory may storeprograms for processing/controlling the operations according to theembodiments, and the processor may control various operations describedin this specification. The processor may be referred to as a controlleror the like. In embodiments, operations may be performed by firmware,software, and/or combinations thereof. The firmware, software, and/orcombinations thereof may be stored in the processor or the memory.

The operations according to the above-described embodiments may beperformed by the transmission device and/or the reception deviceaccording to the embodiments. The transmission/reception device mayinclude a transmitter/receiver configured to transmit and receive mediadata, a memory configured to store instructions (program code,algorithms, flowcharts and/or data) for the processes according to theembodiments, and a processor configured to control the operations of thetransmission/reception device.

The processor may be referred to as a controller or the like, and maycorrespond to, for example, hardware, software, and/or a combinationthereof. The operations according to the above-described embodiments maybe performed by the processor. In addition, the processor may beimplemented as an encoder/decoder for the operations of theabove-described embodiments.

[Mode for Disclosure]

As described above, related details have been described in the best modefor carrying out the embodiments.

INDUSTRIAL APPLICABILITY

As described above, the embodiments are fully or partially applicable toa point cloud data transmission/reception device and system.

Those skilled in the art may change or modify the embodiments in variousways within the scope of the embodiments.

Embodiments may include variations/modifications within the scope of theclaims and their equivalents.

What is claimed is:
 1. An apparatus for receiving point cloud data, theapparatus comprising: a receiver configured to receive point cloud data;a decapsulator configured to decapsulate the point cloud data, thedecapsultor parsing one or more tracks including the point cloud data,the one or more tracks including 3D region information for the pointcloud data; and a decoder configured to decode the point cloud data. 2.The apparatus of claim 1, wherein the 3D region information includes:information representing a number of track groups associated with a 3Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 3Dregion.
 3. The apparatus of claim 1, wherein the one or more tracks aregrouped, wherein the grouped tracks correspond to a 2D region for thepoint cloud data.
 4. The apparatus of claim 3, wherein the one or moretracks a track group box representing the grouped tracks, wherein thegrouped tracks include a same track group identifier.
 5. The apparatusof claim 1, wherein the one or more tracks include 3D region mappinginformation, wherein the 3D region mapping information includes:information representing a number of track groups associated with a 2Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 2Dregion.
 6. A method for receiving point cloud data, the methodcomprising: receiving point cloud data; decapsulating the point clouddata, the decapsulating including parsing one or more tracks includingthe point cloud data, the one or more tracks including 3D regioninformation for the point cloud data; and decoding the point cloud data.7. The method of claim 6, wherein the 3D region information includes:information representing a number of track groups associated with a 3Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 3Dregion.
 8. The method of claim 6, wherein the one or more tracks aregrouped, wherein the grouped tracks correspond to a 2D region for thepoint cloud data.
 9. The method of claim 8, wherein the one or moretracks a track group box representing the grouped tracks, wherein thegrouped tracks include a same track group identifier.
 10. The method ofclaim 6, wherein the one or more tracks include 3D region mappinginformation, wherein the 3D region mapping information includes:information representing a number of track groups associated with a 2Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 2Dregion.
 11. A method for transmitting point cloud data, the methodcomprising: encoding point cloud data; encapsulating the point clouddata, the encapsulating generating one or more tracks including thepoint cloud data, the one or more tracks including 3D region informationfor the point cloud data; and transmitting the point cloud data.
 12. Themethod of claim 11, wherein the 3D region information includes:information representing a number of track groups associated with a 3Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 3Dregion.
 13. The method of claim 11, wherein the one or more tracks aregrouped, wherein the grouped tracks correspond to a 2D region for thepoint cloud data.
 14. The method of claim 13, wherein the one or moretracks a track group box representing the grouped tracks, wherein thegrouped tracks include a same track group identifier.
 15. The method ofclaim 11, wherein the one or more tracks include 3D region mappinginformation, wherein the 3D region mapping information includes:information representing a number of track groups associated with a 2Dregion for the point cloud data; and information identifying a trackgroup for tracks carrying point cloud data associated with the 2Dregion.